feat(dist): crates.io + binstall + Windows install.ps1 + license files

Distribution prep on the road to public availability (plan steps 2–3a).

- Cargo.toml: publish-ready (drop publish=false; homepage/keywords/
  categories/exclude) + [package.metadata.binstall] with per-target
  overrides (linux-gnu->musl, windows-msvc->gnu/gnullvm). dry-run clean.
- scripts/install.ps1: Windows `irm | iex` one-liner — written but
  untested here (no PowerShell; validate on Windows). README Windows block.
- README.md (new); LICENSE-MIT + LICENSE-APACHE (dual, (c) Lazy
  Evaluation Ltd); CONTRIBUTING.md (inbound=outbound dual-license note).
- ADR-0055 Amendment 1 (install.ps1), ADR-0056 (crates.io/binstall),
  README index + plan updates.

The actual `cargo publish` remains a gated maintainer step (token,
irreversible) at a new tagged release; real cargo-binstall validation
pending.

docs/plans/20260616-public-availability.md

@@ -39,9 +39,13 @@ end-to-end against the live public `v0.1.0` release: platform mappings
 (Linux/macOS × x86_64/aarch64; Windows + unknown arch error cleanly),
 pinned (`RDBMS_VERSION`) and latest (`releases/latest`) paths, SHA-256
 verification (incl. a tamper-rejection check), install to
-`~/.local/bin`, PATH hint. **`install.ps1` (Windows) deferred** — Windows
-users go via Scoop/winget (§3). The website copy that references the
-`curl` command is the **website branch's** job (separate agent), later.
+`~/.local/bin`, PATH hint. **`install.ps1` (Windows) added 2026-06-17**
+(user chose both a one-liner *and* Scoop/winget; ADR-0055 Amendment 1):
+`irm | iex`, maps host CPU → our `*-windows-gnu`/`-gnullvm` `.exe`,
+SHA-256-verifies, installs to `%LOCALAPPDATA%\Programs\…` + user PATH —
+**written but untested from this env** (no PowerShell; validate on
+Windows). The website copy that references these commands is the
+**website branch's** job (separate agent), later.
 A **shellcheck CI gate** for `scripts/` is a recommended follow-up (not
 added — shellcheck isn't in the flake yet; touches ADR-ci-002).
 
@@ -78,7 +82,18 @@ Original decided shape (for reference):
 Common thread: a manifest pointing at our checksummed assets + a
 per-release step to bump it. Ordered cheapest → most gatekept.
 
-### 3a. `cargo binstall`
+### 3a. `cargo binstall` + crates.io — PREPARED 2026-06-17 (ADR-0056)
+
+**Done (prep):** crate made publish-ready (dropped `publish = false`;
+added `homepage`/`keywords`/`categories`/`exclude`; authored `README.md`
++ `LICENSE-MIT`); `[package.metadata.binstall]` added with per-target
+overrides (linux-gnu→musl, windows-msvc→gnu/gnullvm; macOS direct);
+`cargo publish --dry-run` clean (913 KiB compressed). Dual license kept;
+`LICENSE-MIT` + `LICENSE-APACHE` (© Lazy Evaluation Ltd) + `CONTRIBUTING.md`
+(inbound=outbound) all in place. **Gated / remaining:** the actual `cargo
+publish` (token, irreversible) at a **new tagged release** (not 0.1.0); a
+real `cargo binstall` validation.
+
 - **Bootstrapping matters (user-flagged):** `binstall` is **not** a
   built-in cargo subcommand — users must install **`cargo-binstall`**
   first (its own `curl|sh`/PowerShell installer, or
@@ -167,10 +182,12 @@ per-release step to bump it. Ordered cheapest → most gatekept.
    command + CI tag-match guard + tests.
 2. ✅ **`scripts/install.sh`** (ADR-0055) — built + verified against the
    live public release.
-3. **← next:** package managers, cheapest first: `cargo binstall`
-   (+ crates.io publish) + Scoop → Homebrew (`lazyeval` tap) → winget
-   (komac / manual). Two `lazyeval` repos (tap + bucket) + CI push creds
-   to set up.
+3. Package managers, cheapest first:
+   - ✅ **`cargo binstall` + crates.io** — *prepared* (ADR-0056);
+     publish gated on a new tagged release + the token.
+   - **← next:** Scoop (`lazyeval` bucket) → Homebrew (`lazyeval` tap) →
+     winget (komac / manual). Two `lazyeval` repos (tap + bucket) + CI
+     push creds to set up.
 4. **Cut a release at a new version** — bump `Cargo.toml` (0.1.0 →
    0.1.1/0.2.0; the ADR-0054 guard checks the tag), tag, push; the four
    Linux/Windows targets build immediately. (macOS leg awaits signing.)