* feat(rag): Phase 2 — ChromaDB vector index over bulk card DB
* feat(rag): add routes/rag.py with build, search, status endpoints
* Update lab_api.pyfeat(rag): register rag_router in lab_api.py, remove old inline rag_status
* Update requirements.txtfeat(rag): add chromadb>=0.5.0 to requirements.txtfeat(rag): add chromadb to requirements.txt
Both were missing from [project.dependencies] in pyproject.toml and
requirements.txt. httpx is used in web/routers/art.py, and websockets
is needed for the FastAPI WebSocket endpoints in ws.py and lobby.py.
Closes#37