Add 4 REST endpoints for RAG database management: GET /documents, GET /documents/{id}/chunks, DELETE /documents/{id}, DELETE /chunks/{id}. Register documents router in main.py. 8 unit tests covering all CRUD operations.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>
Woody