feat(ci): packaging, release and the frozen manifest

Phase 2 of docs/modules/rust/PLAN.md. Phase 1 built five guards and ran them by
hand; this repo had no workflows at all, so nothing gated the branch that gets
released and there was no way to release it.

Three pieces:

- **release.yml** — the derived-version engine link, installer and Module-uo
  already run (conventional-commit subjects since the newest tag; module.json's
  version survives as a floor; workflow_dispatch as the backdoor), assembling the
  bundle from an include list and publishing the tarball, the install manifest
  carrying its sha256, and SHA256SUMS. The tag is the number that ships and CI
  stamps it into the bundle's own module.json.
- **pr-checks.yml** — server tests, check:imports, check:bundle, check:swagger,
  the client build, client tests and check:externals, plus frozen-manifest.
- **frozen-manifest** — clones core at the sha pinned in ci/core-ref.json,
  generates its route table without this module and with it, and takes the
  difference. It ran locally against that exact ref: six routes, all documented,
  no core route moved. That is the first proof by a running core that /rust
  collides with nothing — phase 1 could only check it by reading, because core
  mounts /status and /version at a tier root where the loader's own collision
  probe cannot see them.

The bundle carries no node_modules, because the shipped half declares no runtime
dependencies (org lead, phase 2). checkBundle.js holds both halves of that: the
include list still covers everything server/index.js reaches, and no dependency
has appeared without the release learning to pack it. Verified by breaking it —
dropping "model" from the list names the exact edit and exits 1.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016wDDVXWMDz82WqE1i969r4

server/package.json

@@ -8,6 +8,7 @@
   "scripts": {
     "test": "node --test",
     "check:imports": "node scripts/checkImports.js",
+    "check:bundle": "node scripts/checkBundle.js",
     "swagger": "node scripts/swaggerFragment.js",
     "check:swagger": "node scripts/swaggerFragment.js --check"
   },