RepoGuardian RHD Public Web

Public Vercel + Neon deployment.\n\nWeb app: https://repoguardian-rhd.vercel.app\nAPI: https://repoguardian-rhd-api.vercel.app\nAPI docs: https://repoguardian-rhd-api.vercel.app/docs\n\nIncludes Vercel FastAPI serverless entrypoint, Neon PostgreSQL/pgvector migrations, Postgres-backed jobs, public rate limiting, read-only public write guards, persisted anonymous sessions, public architecture page, and deterministic RHD fallback.