- Create llm_keys.py: GET list (redacted, key_hint only), POST (encrypt + store), DELETE (204 or 404)
- LlmKeyResponse never exposes encrypted_key or raw api_key
- 409 returned on duplicate (tenant_id, provider) key
- Cross-tenant deletion prevented by tenant_id verification in DELETE query
- Update api/__init__.py to export llm_keys_router
- All 5 LLM key CRUD tests passing (32 total unit tests green)