feat(agent): add recommendation confidence provenance

[mkdev5]

Summary

• Adds private payload.recommendationEvidence to agent action records with confidence, source provenance, freshness, assumptions, warnings, and user-supplied scenario markers.
• Lowers recommendation confidence for stale decision packs, degraded/blocked signals, missing official stats/outcomes, and uncertain local branch metadata.
• Keeps public GitHub rendering sanitized by continuing to render from publicSafeSummary while private API/MCP structured content carries provenance.

Closes #95

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.

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 auth, session, deploy, public docs, changelog, or visible UI behavior changed; those checklist items are satisfied as not applicable.
• npm run test:coverage: statements 98.98%, branches 97.09%, functions 98.09%, lines 99.61%.
• npm run test:ci also passed end to end, including workers, MCP pack/build, UI checks, and audit.

[JSONbored]

@MkDev11 this is a useful agent reliability improvement.

A few notes:

• The confidence payload gives private API/MCP consumers enough provenance to judge stale or degraded recommendations.
• Public output remains on publicSafeSummary, so the private evidence does not leak into GitHub comments.
• The tests cover decision-pack, local-branch, and default evidence behavior.
• No code changes requested.

Validation expected:

• Current GitHub checks are green.