Merge branch 'main' into website (Gitea migration + ADR renumber)

Brings website up to date with main (18 commits): H1a parse-error
pedagogy, V5/H3/V5a show+help commands, ADR-0043 compound-PK FK,
handoffs 58-59, and the GitHub->Gitea doc scrub (Cargo.toml repository,
CLAUDE.md, ADR-0001 amendment, requirements).

Conflict: docs/adr/README.md. main and website had each created an
ADR-0042 (main: H1a parse-error pedagogy; website: public website &
docs site). Renumbered the website ADR to 0044 (next free after main's
0042/0043) and updated all references (ADR file, plan file, STYLE.md,
astro.config.mjs, README index). Website build verified green.

website/STYLE.md

@@ -4,7 +4,7 @@ This is the **living** home for documentation authoring conventions for the
 RDBMS Playground website. It grows as we write.
 
 - **Binding rules** come from
-  [ADR-0042 §7](../docs/adr/0042-public-website-and-documentation-site.md);
+  [ADR-0044 §7](../docs/adr/0044-public-website-and-documentation-site.md);
   this guide must not contradict them. If a convention is significant,
   durable, or contested, it is decided in an **ADR** (new or amended), and
   this guide references it. Finer, settled conventions live here directly.
@@ -17,7 +17,7 @@ Status tags used below: **[DECIDED]** (binding or settled) ·
 
 ---
 
-## Terminology & wording  [DECIDED — ADR-0042 §7]
+## Terminology & wording  [DECIDED — ADR-0044 §7]
 
 - **No "DSL".** It is internal jargon. Use **simple mode** (the playground's
   keyword command language) and **advanced mode** (SQL).
@@ -60,7 +60,7 @@ Ground every reference page in source — `parse.usage.*` and `help.*` in
 `src/friendly/strings/en-US.yaml`, `src/dsl/command.rs`, `src/dsl/types.rs`
 — never paraphrase grammar from memory.
 
-## "Planned / not yet available" callouts  [DECIDED — ADR-0042 §7]
+## "Planned / not yet available" callouts  [DECIDED — ADR-0044 §7]
 
 Any capability that is not yet fully implemented is **omitted** or carries a
 clear callout — never presented as shipped. Standard form: a Starlight aside
@@ -104,7 +104,7 @@ a small standalone example, not by complicating this schema.
 - Pair a hero/landing cast with a text transcript or the equivalent docs
   snippet (accessibility + SEO).
 - Recorded via a scripted-input driver for paced, re-recordable sessions
-  (ADR-0042 §2; recipe in `README.md`). **[OPEN]**: cast file naming,
+  (ADR-0044 §2; recipe in `README.md`). **[OPEN]**: cast file naming,
   fixed terminal size, light/dark theme handling.
 
 ## Formatting  [DECIDED, refine]