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.

LICENSE-MIT

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 Lazy Evaluation Ltd
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.