feat(signals): surface bounty opportunity reconciliation - #370

Summary

• Add structured bounty/opportunity reconciliation context to issue-quality entries, including lifecycle, active-opportunity status, funding state, source freshness, and linked PR state.
• Extend bounty advisories with source freshness metadata and include recent merged PR evidence when reconciling linked PR state.
• Update OpenAPI/UI OpenAPI and regression tests so private API/MCP consumers can avoid stale or already-worked bounty opportunities without parsing prose warnings.
• Closes feat(signals): add bounty and opportunity stale-source reconciliation #112.

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 99.08%, branches 97.04%, functions 98.43%, lines 99.65%.

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.
• Public GitHub output is unchanged; this is private API/MCP structured signal data plus OpenAPI schema updates.