feat(signals): add queue pressure trend windows

[grnlemon]

Summary

• Add compact queue pressure trend snapshots generated from bounded GitHub totals and queue-health history.
• Surface 7/14/30 day queue growth, review velocity, stale-rate, and duplicate-pressure trends through private repo intelligence and MCP context.
• Return an unavailable trend state when history is missing; private request paths read the compact snapshot instead of scanning historical source rows.
• Closes feat(signals): add queue pressure and review velocity trend windows #110.

Scope

• This PR is focused and does not mix unrelated backend, UI, MCP, docs, dependency, and deploy changes.
• This follows CONTRIBUTING.md and does not reintroduce GitHub Pages, VitePress, site/, or CNAME.
• I linked an issue, or this is small enough that the summary explains why an issue is not needed.

Validation

• git diff --check
• npm run actionlint
• npm run typecheck
• npm run test:coverage locally; global coverage stays at or above 97% for lines, statements, functions, and branches (aim for 98%+ branch coverage locally so CI variance does not fail near the threshold)
• npm run test:workers
• npm run build:mcp
• npm run test:mcp-pack
• npm run ui:openapi:check
• npm run ui:lint
• npm run ui:typecheck
• npm run ui:build
• npm audit --audit-level=moderate
• New or changed behavior has unit/integration tests for new branches, fallback paths, and sanitizer boundaries

If any required check was skipped, explain why:

• None. Full npm run test:ci passed locally. Coverage summary: statements 99.1%, branches 97.01%, functions 98.44%, lines 99.66%.

Safety

• No secrets, wallet details, hotkeys, coldkeys, user PATs, private keys, raw trust scores, private rankings, or private maintainer evidence are exposed.
• Public GitHub text stays sanitized, low-noise, and does not imply compensation guarantees or optimization tactics.
• Auth, cookie, CORS, GitHub App, Cloudflare, or session changes include negative-path tests.
• API/OpenAPI/MCP behavior is updated and tested where needed.
• UI changes use live API data or real empty/error/loading states, not production mock/demo fallbacks.
• Visible UI changes include screenshots or a short recording.
• Public docs/changelogs are updated where needed; changelogs are only edited for release-prep PRs.

Notes

• No visible UI changes; the UI build only validates the regenerated OpenAPI contract and extension packaging.
• The new trend snapshot is generated during bounded signal snapshot processing and consumed by private repo intelligence/MCP on request paths.

[JSONbored]

@MkDev11 this looks ready from this pass.

A few notes:

• Queue trend windows are aligned with the current maintainer-intelligence direction.
• The implementation persists compact trend snapshots instead of forcing request-time history scans.
• API, MCP, schema, migration, and tests are updated together.

No code changes requested.