feat(review): surface generate-tests command inline in the review comment

[JSONbored]

Summary

• Epic Epic: AI-generated E2E test coverage for pull requests #4189 (AI-generated E2E test coverage) is code-complete — @gittensory generate-tests and the
  manifest_missing_tests auto-trigger both work — but nothing in ORB's own review comment ever told a
  maintainer the command exists. A maintainer would have to already know it from documentation.
• CodeRabbit's own equivalent avoids this exact gap: their "Generate unit tests" affordance is a
  checkbox inside their own PR walkthrough comment, not a separate dashboard toggle — discoverable at
  the point a maintainer is already looking.
• publicSafeManifestPolicyFinding (src/queue/processors.ts) now accepts an optional
  { e2eTestGenAvailable } and, only for the manifest_missing_tests finding and only when the
  e2eTests converged feature is actually enabled for the repo, appends a short CTA to that finding's
  rendered action text: "Maintainers can also comment @gittensory generate-tests for an AI-generated
  Playwright test."
• The gating check (resolveConvergedFeature(env, manifest, "e2eTests", repoFullName)) is hoisted once
  and reused by the existing feat(review): auto-trigger E2E test generation on the manifest_missing_tests signal #4196 auto-trigger if immediately below it, rather than computed twice.
• No new UI surface, no dashboard — text-only, inline in the comment ORB already posts. Byte-identical
  output for every repo that doesn't have e2eTests enabled.

Fixes #4583

Test plan

• test/unit/public-safe-manifest-finding.test.ts: 2 new cases — CTA appended when
  e2eTestGenAvailable: true on manifest_missing_tests; CTA never leaks onto an unrelated finding
  code even when e2eTestGenAvailable: true — plus the 2 pre-existing cases (redaction, pass-through)
  continue to cover the default/omitted-options path unchanged
• Full test/unit/queue.test.ts (768 tests, including the existing manifest_missing_tests auto-trigger (#4196) describe block) — all pass, confirming the hoisted e2eTestGenAvailable
  const is behavior-preserving for the auto-trigger
• Verified via lcov branch data (BRDA) that both branches of the new if are exercised and no
  branch introduced by this diff is left uncovered
• npx tsc --noEmit clean on this diff (a pre-existing, unrelated typecheck failure in
  test/unit/miner-attempt-log.test.ts predates this branch — confirmed via git diff origin/main
  showing zero changes to that file)
• git diff --check clean; no drift against origin/main at push time
• No generated artifacts invalidated (no API/OpenAPI, wrangler binding, Drizzle schema, selfhost
  env-read, or CLI command-surface changes)

[superagent-security]

Superagent didn't find any vulnerabilities or security issues in this PR.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.12%. Comparing base (6e1493a) to head (1bfac9a).
⚠️ Report is 2 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4586   +/-   ##
=======================================
  Coverage   94.12%   94.12%           
=======================================
  Files         430      430           
  Lines       38167    38173    +6     
  Branches    13917    13919    +2     
=======================================
+ Hits        35924    35930    +6     
  Misses       1585     1585           
  Partials      658      658           

Files with missing lines	Coverage Δ
src/queue/processors.ts	95.31% <100.00%> (+<0.01%)	⬆️

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