Fix public answer search when anonymous limiter is unavailable

[BigSimmo]

Summary

• Keep unauthenticated answer/search/read requests working by falling back to the in-memory limiter when the durable anonymous limiter is unavailable.
• Preserve fail-closed behavior for authenticated owner-scoped limits and non-read anonymous buckets unless the existing production/local fallback flag applies.
• Add a visible non-production demo fallback for invalid Supabase API-key configuration across /api/search, /api/answer, and streamed /api/answer/stream, while production remains fail-closed.
• Add regression coverage for anonymous search, non-streamed answers, streamed answers, upload fallback boundaries, and production guards.

Verification

• npm run verify:cheap
• npm run verify:ui when UI, routing, styling, browser behavior, reduced-motion, or forced-colors behavior changed
• npm run verify:release before release or handoff confidence claims
• npm run format:check
• npm run eval:retrieval:quality (must stay 23/23) when retrieval, ranking, selection, chunking, or scoring behavior changed — not run; rate-limit/fallback access fix does not change retrieval/ranking/scoring.
• npm run eval:rag -- --limit 15 + npm run eval:quality -- --rag-only when answer generation, the synthesis prompt, or answer post-processing changed — not run; no synthesis/prompt/post-processing changes.
• npm run check:production-readiness when clinical workflow, privacy, environment, Supabase, source governance, or deployment behavior changed
• npm run check:deployment-readiness when deployment startup, hosting, or rollout behavior changed

Clinical Governance Preflight

• Source-backed claims still require linked source verification before clinical use
• No patient-identifiable document workflow was introduced or expanded without explicit governance approval
• Supabase target remains Clinical KB Database (sjrfecxgysukkwxsowpy)
• Service-role keys and private document access remain server-only
• Demo/synthetic content remains clearly separated from real clinical sources
• Source metadata, review status, and outdated/unknown-source behavior remain conservative
• Deployment classification/TGA SaMD impact was checked when clinical decision-support behavior changed

Notes

• Current Cloud Agent Supabase keys are rejected by Supabase as an unregistered API key; this PR keeps non-production/preview search usable with clearly marked synthetic fallback data, but production still requires corrected live Supabase secrets.

  

[supabase]

This pull request has been ignored for the connected project sjrfecxgysukkwxsowpy because there are no changes detected in supabase directory. You can change this behaviour in Project Integrations Settings ↗︎.

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