fix: cut GitHub API spend on coverage, etags, feedback, CI, and releases

[jeremymcs]

Summary

Stops PatchDeck from burning GitHub quota on repeated reads of data it already has.

• Issue coverage no longer hits GET /search/issues on every UI poll. The Issues page reads persisted githubOpenCount from the issue sweep (GraphQL totalCount, ~1 point).
• Open PR lists persist etag + summaries so a process restart is a 304, not a full pagination.
• Issue sweeps reuse the conditional page-1 body instead of fetching page 1 twice.
• PR comment/review lists are probed with If-None-Match; an all-304 skips the nested review-thread GraphQL query. Nested comment pages drop from 100 to 20.
• Settled commit SHA CI (statuses + check runs) is loaded once per Octokit client.
• listMergedPullsSince stops paging closed PRs once updated_at is older than the since bound.

Commits

1. fix: stop Search API polling for issue coverage
2. fix: persist PR list etags and reuse issue page 1
3. fix: skip review-thread GraphQL when PR comments are unchanged
4. fix: reuse settled CI status fetches for a commit SHA
5. fix: stop paging closed PRs once the release since-bound is passed

Plan: docs/plans/github-rate-limit-cache.md

Test plan

• npm test (715 passing)
• npx tsx --test client/src/lib/*.test.ts (90 passing)
• npm run check
• With the dashboard running, open Issues and confirm synced N / GitHub M still renders after a sweep. /api/issues/coverage should not call Search.

[github-actions]

📄 Documentation Review Reminder

This PR changes source files but does not update any public documentation.

Changed source files:

client/src/lib/fullAppQaSurface.test.ts
client/src/pages/issues.tsx
server/appRuntime.test.ts
server/appRuntime.ts
server/babysitter.test.ts
server/babysitter.ts
server/github.test.ts
server/github.ts
server/memoryStorage.ts
server/sqliteStorage.ts
server/storage.test.ts
server/storage.ts

Please check if documentation in docs/public/ needs to be updated:

• No documentation update needed
• Documentation updated in this PR
• Follow-up documentation issue created

Public docs are Markdown files in docs/public/. They are automatically
rendered to HTML and deployed to GitHub Pages when merged to main.

Available docs: getting-started.md, pr-babysitter.md, agent-dispatch.md, configuration.md, pr-questions.md