Fix audit log: correct API params + field name mapping

Fix SourceCard: map backend field names (document, page, similarity)

Fix JSONB cast syntax for asyncpg (::jsonb → CAST)

Switch to llama-3.3-70b-versatile (3.1 decommissioned)

Fix uploaded_at: make nullable in response + set NOW() on insert

Fix upload endpoint: /api/documents → /api/documents/upload

Fix openai/httpx version conflict (proxies kwarg)

Switch to fully free stack: Groq + local fastembed (no OpenAI needed)

Complete backend services + React frontend dashboard

Initial scaffold: FastAPI + pgvector + trust verification architecture