chore: scaffold website (Astro 6 + Starlight + Tailwind v4)

Phase A of docs/plans/20260604-adr-0042-website.md. Scaffolds the site
under website/ from the Starlight template; adds Tailwind v4 (via
@tailwindcss/vite) bridged to Starlight with @astrojs/starlight-tailwind
(src/styles/global.css + customCss). Production build is green: static
output, Pagefind search index, sharp image optimization.

Template placeholders (title, example pages, sidebar) are left for
Phase B/D. Reconciles the ADR/plan/index wording from "Astro 5" to
"Astro 6" to match the scaffolded toolchain.

docs/adr/0042-public-website-and-documentation-site.md

@@ -26,7 +26,7 @@ planning + `/runda` pass with the user and are recorded below.
 
 ## Decision
 
-1. **Stack — Astro 5 + Starlight + Tailwind v4.** Astro's content-first,
+1. **Stack — Astro 6 + Starlight + Tailwind v4.** Astro's content-first,
    zero-JS-by-default model with the Starlight docs theme fits a
    marketing-landing-plus-heavy-docs site better than the alternative
    considered, SvelteKit + Tailwind (the usual go-to here). Interactive
@@ -65,7 +65,7 @@ planning + `/runda` pass with the user and are recorded below.
      and the rusqlite **backup-API** undo (ADR-0006) → a SQL dump/restore.
    When taken up, this becomes its own ADR + iteration plan.
 
-4. **Hosting — portable static build; Vercel is the likely target.** Astro 5
+4. **Hosting — portable static build; Vercel is the likely target.** Astro 6
    builds to static HTML/CSS with no adapter, so the output deploys equally
    to Vercel, Cloudflare Pages, Netlify, or GitHub Pages. We avoid coupling
    to any one host. **No CI yet** — the site is tested locally (`pnpm dev` /

docs/adr/README.md

@@ -47,4 +47,4 @@ This directory contains the project's ADRs, recorded per
 - [ADR-0039 — EXPLAIN over advanced-mode SQL queries](0039-explain-over-advanced-sql.md) — **Accepted** (2026-05-27), **implemented 2026-05-30 (issue #7)**, **supersedes ADR-0030 §13 OOS-2**. Lets `explain` wrap the advanced SQL commands (`Select`/`SqlInsert`/`SqlUpdate`/`SqlDelete`, plus `with`/CTE which builds a `Select`) in addition to the DSL `ShowData`/`Update`/`Delete` it already covers (ADR-0028), running `EXPLAIN QUERY PLAN` over the validated SQL text through the existing ADR-0028 span-styled plan tree (advanced mode only; DSL `explain` unchanged in both modes). Implemented via a second `Advanced` `explain` CommandNode (`EXPLAIN_SQL`) registered under the shared `explain` entry word — reusing the established `insert`/`update`/`delete` shared-word dispatch (`decide`: SQL-first / DSL-fallback), so `explain show data …` and DSL-only `--all-rows` still reach the DSL node; rejected a `DynamicSubgrammar` mode-gate (its resolution cache key omits `mode`). `build_explain_sql` slices the inner SQL off the source (excludes `explain`) and reuses the existing SQL builders; `do_explain_plan` runs the carried text verbatim, no params. Advanced `explain update`/`delete` now route through SQL (identical plan, full SQL syntax); DSL-explain tests pinned to simple mode. Reframed OOS-2 as a *deferred* exclusion (per ADR-0000's out-of-scope discipline), not a rejection. OOS (deferred): EXPLAIN of DDL (no query plan exists)
 - [ADR-0040 — A per-command completion marker (✓/✗) replaces the `[ok]` summary line](0040-completion-marker-replaces-ok-summary.md) — **Accepted 2026-05-30 (issue #9)**, amends ADR-0014 / ADR-0028 / ADR-0019 output conventions, builds on ADR-0037's mode-tagged echo. An audit of the whole command surface found the `[ok] <verb> <subject>` summary line duplicates the echo line above it (verb+subject) everywhere; its only unique contribution is the success-vs-error signal (and `explain select` even rendered `[ok] explain` with an empty subject post-ADR-0039). Decision: drop the `[ok]` line and the symmetric `"…" failed:` prefix; the echo line gains a trailing inline **✓** (green, success) / **✗** (red, failure) — `running:` becomes a pending state that resolves to `<input> ✓/✗` on completion (status set via the existing `rfind(Echo)` lookup). Content (row counts, structure, data, plan tree, teaching echo) unchanged. Scoped to the DSL/data/SQL family that has the redundant echo+`[ok]` pair; app-command `[ok]` lines (`rebuild`/`export`/`now editing`) are payload-bearing, have no echo to mark, and stay as-is. `ok.summary` retired; `dsl.failed` reduced to the rendered reason. Broad but mechanical snapshot churn. OOS: app-command `[ok]` lines, the `[WRN]` validity indicator, and the tag colours (issue #10)
 - [ADR-0041 — Copy the output panel to the system clipboard](0041-copy-output-to-clipboard.md) — **Accepted 2026-06-02 (issue #11)**, amends ADR-0003's app-command registry (adds **`copy`** / `copy all` / `copy last`). The friction it removes: filing a bug report meant terminal-selecting the output panel and fighting wrapping/borders. New **app-level command** (sigil-free, both modes): `copy` / `copy all` copy the whole panel; `copy last` copies from the most recent echo line to the end. **Mechanism — OSC 52 *and* native (`arboard`), always both**, because OSC 52 acceptance is undetectable (no terminal ack), so a true "fall back when unsupported" can't be built: emit the OSC 52 escape (no new dep — `base64`+`crossterm`; works over SSH; tmux-passthrough-wrapped via `$TMUX`), then a best-effort native write whose failure is ignored (headless host — OSC 52 carried it); the two carry identical content. **Format — plain text verbatim as rendered** (tags, `✓`/`✗`, box-drawing) joined by `\n`, without viewport padding/wrapping; a drift-lock test pins `OutputLine::plain_text` to `render_output_line`. `arboard` added **`--no-default-features`** (drops the `image` crate; X11-only on Linux — `wayland-data-control` deliberately omitted as it ~doubles the dep tree and OSC 52 covers native-Wayland). Security: write-only, scans clean for arboard's tree (cargo audit / osv-scanner / grype), 1Password-maintained, minimal surface. OOS: Markdown export, selection/range, a keybinding, OSC 52 read, `screen` passthrough
-- [ADR-0042 — Public website and documentation site](0042-public-website-and-documentation-site.md) — **Accepted 2026-06-04**. The first public website: a marketing landing page plus the **canonical** user docs. Stack **Astro 5 + Starlight + Tailwind v4** (chosen over SvelteKit + Tailwind for a docs-heavy + marketing site; interactive bits as Astro islands). Showcase demos are **asciinema** `.cast` recordings (scripted-input driver for paced, re-recordable sessions — *not* `history.log` replay), reused inline in docs. The **in-page WASM playground is deferred** (OOS: deferred) behind a stable `Demo` seam, with the portable-core (`dsl`/`app`/`ui`, in-memory `rusqlite` via `ffi-sqlite-wasm-rs`) vs native-edge (Tokio/worker-thread/`crossterm`/persistence/backup-API) boundary recorded for a future ADR + iteration plan. Portable **static build** (Vercel target, but host-agnostic); **no CI yet**; **monorepo** (`website/`). Docs cover the **full supported feature set** with "planned" callouts for the unshipped minority; two wording rules bind user-facing copy — **no engine name** (continues ADR-0002) and **no "DSL"** ("simple mode" / "advanced mode"). Install docs cover **prebuilt binaries + package managers** (D1–D3 track the release tooling). Plan: `docs/plans/20260604-adr-0042-website.md`
+- [ADR-0042 — Public website and documentation site](0042-public-website-and-documentation-site.md) — **Accepted 2026-06-04**. The first public website: a marketing landing page plus the **canonical** user docs. Stack **Astro 6 + Starlight + Tailwind v4** (chosen over SvelteKit + Tailwind for a docs-heavy + marketing site; interactive bits as Astro islands). Showcase demos are **asciinema** `.cast` recordings (scripted-input driver for paced, re-recordable sessions — *not* `history.log` replay), reused inline in docs. The **in-page WASM playground is deferred** (OOS: deferred) behind a stable `Demo` seam, with the portable-core (`dsl`/`app`/`ui`, in-memory `rusqlite` via `ffi-sqlite-wasm-rs`) vs native-edge (Tokio/worker-thread/`crossterm`/persistence/backup-API) boundary recorded for a future ADR + iteration plan. Portable **static build** (Vercel target, but host-agnostic); **no CI yet**; **monorepo** (`website/`). Docs cover the **full supported feature set** with "planned" callouts for the unshipped minority; two wording rules bind user-facing copy — **no engine name** (continues ADR-0002) and **no "DSL"** ("simple mode" / "advanced mode"). Install docs cover **prebuilt binaries + package managers** (D1–D3 track the release tooling). Plan: `docs/plans/20260604-adr-0042-website.md`

docs/plans/20260604-adr-0042-website.md

@@ -3,7 +3,7 @@
 **Date:** 2026-06-04 · **Status:** ready to build
 
 Decisions for this work are recorded in
-[ADR-0042](../adr/0042-public-website-and-documentation-site.md): Astro 5 +
+[ADR-0042](../adr/0042-public-website-and-documentation-site.md): Astro 6 +
 Starlight + Tailwind v4; asciinema demos reusable in docs; the in-page WASM
 playground deferred behind a stable demo seam; portable static hosting
 (Vercel target); monorepo (`website/`); website is the canonical docs home;

website/.gitignore

@@ -0,0 +1,21 @@
+# build output
+dist/
+# generated types
+.astro/
+
+# dependencies
+node_modules/
+
+# logs
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+
+
+# environment variables
+.env
+.env.production
+
+# macOS-specific files
+.DS_Store

website/.vscode/extensions.json

@@ -0,0 +1,4 @@
+{
+  "recommendations": ["astro-build.astro-vscode"],
+  "unwantedRecommendations": []
+}

website/.vscode/launch.json

@@ -0,0 +1,11 @@
+{
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "command": "./node_modules/.bin/astro dev",
+      "name": "Development server",
+      "request": "launch",
+      "type": "node-terminal"
+    }
+  ]
+}

website/README.md

@@ -0,0 +1,49 @@
+# Starlight Starter Kit: Basics
+
+[![Built with Starlight](https://astro.badg.es/v2/built-with-starlight/tiny.svg)](https://starlight.astro.build)
+
+```
+pnpm create astro@latest -- --template starlight
+```
+
+> 🧑‍🚀 **Seasoned astronaut?** Delete this file. Have fun!
+
+## 🚀 Project Structure
+
+Inside of your Astro + Starlight project, you'll see the following folders and files:
+
+```
+.
+├── public/
+├── src/
+│   ├── assets/
+│   ├── content/
+│   │   └── docs/
+│   └── content.config.ts
+├── astro.config.mjs
+├── package.json
+└── tsconfig.json
+```
+
+Starlight looks for `.md` or `.mdx` files in the `src/content/docs/` directory. Each file is exposed as a route based on its file name.
+
+Images can be added to `src/assets/` and embedded in Markdown with a relative link.
+
+Static assets, like favicons, can be placed in the `public/` directory.
+
+## 🧞 Commands
+
+All commands are run from the root of the project, from a terminal:
+
+| Command                   | Action                                           |
+| :------------------------ | :----------------------------------------------- |
+| `pnpm install`             | Installs dependencies                            |
+| `pnpm dev`             | Starts local dev server at `localhost:4321`      |
+| `pnpm build`           | Build your production site to `./dist/`          |
+| `pnpm preview`         | Preview your build locally, before deploying     |
+| `pnpm astro ...`       | Run CLI commands like `astro add`, `astro check` |
+| `pnpm astro -- --help` | Get help using the Astro CLI                     |
+
+## 👀 Want to learn more?
+
+Check out [Starlight’s docs](https://starlight.astro.build/), read [the Astro documentation](https://docs.astro.build), or jump into the [Astro Discord server](https://astro.build/chat).

website/astro.config.mjs

@@ -0,0 +1,33 @@
+// @ts-check
+import { defineConfig } from 'astro/config';
+import starlight from '@astrojs/starlight';
+
+import tailwindcss from '@tailwindcss/vite';
+
+// https://astro.build/config
+export default defineConfig({
+  integrations: [
+      starlight({
+          title: 'My Docs',
+          social: [{ icon: 'github', label: 'GitHub', href: 'https://github.com/withastro/starlight' }],
+          customCss: ['./src/styles/global.css'],
+          sidebar: [
+              {
+                  label: 'Guides',
+                  items: [
+                      // Each item here is one entry in the navigation menu.
+                      { label: 'Example Guide', slug: 'guides/example' },
+                  ],
+              },
+              {
+                  label: 'Reference',
+                  items: [{ autogenerate: { directory: 'reference' } }],
+              },
+          ],
+      }),
+	],
+
+  vite: {
+    plugins: [tailwindcss()],
+  },
+});

website/package.json

@@ -0,0 +1,21 @@
+{
+  "name": "rdbms-playground-website",
+  "private": true,
+  "type": "module",
+  "version": "0.0.1",
+  "scripts": {
+    "dev": "astro dev",
+    "start": "astro dev",
+    "build": "astro build",
+    "preview": "astro preview",
+    "astro": "astro"
+  },
+  "dependencies": {
+    "@astrojs/starlight": "^0.39.3",
+    "@astrojs/starlight-tailwind": "^5.0.0",
+    "@tailwindcss/vite": "^4.3.0",
+    "astro": "^6.3.1",
+    "sharp": "^0.34.5",
+    "tailwindcss": "^4.3.0"
+  }
+}

website/public/favicon.svg

@@ -0,0 +1 @@
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 128 128"><path fill-rule="evenodd" d="M81 36 64 0 47 36l-1 2-9-10a6 6 0 0 0-9 9l10 10h-2L0 64l36 17h2L28 91a6 6 0 1 0 9 9l9-10 1 2 17 36 17-36v-2l9 10a6 6 0 1 0 9-9l-9-9 2-1 36-17-36-17-2-1 9-9a6 6 0 1 0-9-9l-9 10v-2Zm-17 2-2 5c-4 8-11 15-19 19l-5 2 5 2c8 4 15 11 19 19l2 5 2-5c4-8 11-15 19-19l5-2-5-2c-8-4-15-11-19-19l-2-5Z" clip-rule="evenodd"/><path d="M118 19a6 6 0 0 0-9-9l-3 3a6 6 0 1 0 9 9l3-3Zm-96 4c-2 2-6 2-9 0l-3-3a6 6 0 1 1 9-9l3 3c3 2 3 6 0 9Zm0 82c-2-2-6-2-9 0l-3 3a6 6 0 1 0 9 9l3-3c3-2 3-6 0-9Zm96 4a6 6 0 0 1-9 9l-3-3a6 6 0 1 1 9-9l3 3Z"/><style>path{fill:#000}@media (prefers-color-scheme:dark){path{fill:#fff}}</style></svg>

website/src/content.config.ts

@@ -0,0 +1,7 @@
+import { defineCollection } from 'astro:content';
+import { docsLoader } from '@astrojs/starlight/loaders';
+import { docsSchema } from '@astrojs/starlight/schema';
+
+export const collections = {
+	docs: defineCollection({ loader: docsLoader(), schema: docsSchema() }),
+};

website/src/content/docs/guides/example.md

@@ -0,0 +1,11 @@
+---
+title: Example Guide
+description: A guide in my new Starlight docs site.
+---
+
+Guides lead a user through a specific task they want to accomplish, often with a sequence of steps.
+Writing a good guide requires thinking about what your users are trying to do.
+
+## Further reading
+
+- Read [about how-to guides](https://diataxis.fr/how-to-guides/) in the Diátaxis framework

website/src/content/docs/index.mdx

@@ -0,0 +1,40 @@
+---
+title: Welcome to Starlight
+description: Get started building your docs site with Starlight.
+template: splash # Remove or comment out this line to display the site sidebar on this page.
+hero:
+  tagline: Congrats on setting up a new Starlight project!
+  image:
+    file: ../../assets/houston.webp
+  actions:
+    - text: Example Guide
+      link: /guides/example/
+      icon: right-arrow
+    - text: Read the Starlight docs
+      link: https://starlight.astro.build
+      icon: external
+      variant: minimal
+---
+
+import { Card, CardGrid } from '@astrojs/starlight/components';
+
+## Next steps
+
+<CardGrid stagger>
+	<Card title="Update content" icon="pencil">
+		Edit `src/content/docs/index.mdx` to see this page change.
+	</Card>
+	<Card title="Change page layout" icon="document">
+		Delete `template: splash` in `src/content/docs/index.mdx` to display a
+		sidebar on this page.
+	</Card>
+	<Card title="Add new content" icon="add-document">
+		Add Markdown or MDX files to `src/content/docs` to create new pages.
+	</Card>
+	<Card title="Configure your site" icon="setting">
+		Edit your `sidebar` and other config in `astro.config.mjs`.
+	</Card>
+	<Card title="Read the docs" icon="open-book">
+		Learn more in [the Starlight Docs](https://starlight.astro.build/).
+	</Card>
+</CardGrid>

website/src/content/docs/reference/example.md

@@ -0,0 +1,11 @@
+---
+title: Example Reference
+description: A reference page in my new Starlight docs site.
+---
+
+Reference pages are ideal for outlining how things work in terse and clear terms.
+Less concerned with telling a story or addressing a specific use case, they should give a comprehensive outline of what you're documenting.
+
+## Further reading
+
+- Read [about reference](https://diataxis.fr/reference/) in the Diátaxis framework

website/src/styles/global.css

@@ -0,0 +1,4 @@
+@layer base, starlight, theme, components, utilities;
+@import '@astrojs/starlight-tailwind';
+@import 'tailwindcss/theme.css' layer(theme);
+@import 'tailwindcss/utilities.css' layer(utilities);

website/tsconfig.json

@@ -0,0 +1,5 @@
+{
+  "extends": "astro/tsconfigs/strict",
+  "include": [".astro/types.d.ts", "**/*"],
+  "exclude": ["dist"]
+}