feat(raycast): add metadata-only repo analyzer

[mkdev5]

Summary

• Closes feat(raycast): add metadata-only local repo analyzer #116.
• Adds a metadata-only Raycast local repo analyzer that collects branch refs, base/head/merge-base SHAs, changed-file metadata, test-file counts, validation hints, stale-base warnings, and linked issue references without reading source contents.
• Posts the sanitized metadata payload to the existing /v1/local/branch-analysis API and degrades to structured api_error output when the API is unavailable.
• Rejects source-upload mode and safely handles renamed, copied, binary, deleted, malformed, and missing git metadata paths.

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. npm run test:ci passed locally. Coverage summary: statements 99.08%, branches 97.01%, functions 98.41%, 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; screenshots are not applicable.
• No OpenAPI, MCP, auth, dependency, or release-note changes were needed for this Raycast-side helper.
• The generated apps/gittensory-ui/public/downloads/ artifact from npm run test:ci was intentionally left out of the commit.

[JSONbored]

@MkDev11 this looks good for this slice.

A few notes:

• The local repo analyzer is scoped as Raycast support infrastructure and the tests cover the behavior being introduced.
• I do not see a merge blocker in the current diff or CI.
• No code changes requested from me.

Validation expected:

• Current green CI is enough for this PR.