feat(settings): emit policy readiness warnings

[bitloi]

Summary

• Adds deterministic repo policy readiness warnings from focus manifests and repo context, covering direct-PR policy, issue-discovery posture, validation uncertainty, contribution scope, and maintainer burden.
• Threads public-safe warning text into the existing registration-readiness warnings array while exposing a structured policyReadiness object for owner preview.
• Separates private owner context into counts/metadata only and adds sanitizer tests so private notes and unsafe public text do not leak.

Closes #298

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%, functions 98.35%, 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. No visible UI workflow changes in this PR.
• Public docs/changelogs are updated where needed; changelogs are only edited for release-prep PRs.

Notes

• API contract note: /v1/repos/:owner/:repo/registration-readiness now includes additive policyReadiness data and the generated UI OpenAPI snapshot was refreshed.
• The route reads cached/API-backed focus manifest state for readiness preview and does not perform autonomous GitHub actions.
• This intentionally does not implement the full policy compiler schema, contribution-lane derivation, onboarding export, public scoring, autonomous issue filing, PR creation, comments, labels, closure, or merge behavior.

[JSONbored]

@bitloi this looks ready from my pass.

A few notes:

• The PR stays focused on policy readiness warnings and keeps the output public-safe.
• The owner/private context is represented structurally without leaking private notes into public text.
• OpenAPI and route coverage are updated, and the test coverage matches the linked issue acceptance criteria.

No code changes requested from me.