fix(api): keep queued run comments from expiring plans

[shuntianyifang]

Summary

• Prefix new control-plane and MCP queue acknowledgements with a hidden Facility run marker.
• Ignore queue acknowledgements during issue-revision calculation only when a GitHub Bot posts an exact recognized message.
• Keep legacy markerless Facility acknowledgements compatible while treating user lookalikes, appended content, and mismatched run IDs as material changes.

Why

Closes #222

Facility could count its own queued-run acknowledgement as a new issue revision. An already approved architect plan would then appear stale before the builder started.

Testing

• pnpm --filter @facility/api exec vitest run --fileParallelism=false test/github-issue-revision.test.ts test/builder-plan-policy.integration.test.ts (34 passed, 0 skipped)
• pnpm --filter @facility/api typecheck
• pnpm exec biome check on all five changed files
• git diff --check

The full release-shaped pnpm verify runs in GitHub Actions on Ubuntu with Node.js 22. It is not reported as a Windows-local result because the upstream checkout currently has unrelated Windows-only baseline failures; no repository check or test was disabled.