Implement Sprint 3: Chat Functionality
- Add ChatService with send_message and get_history methods
- Add POST /api/v1/notebooks/{id}/chat - Send message
- Add GET /api/v1/notebooks/{id}/chat/history - Get chat history
- Add ChatRequest model (message, include_references)
- Add ChatResponse model (message, sources[], timestamp)
- Add ChatMessage model (id, role, content, timestamp, sources)
- Add SourceReference model (source_id, title, snippet)
- Integrate chat router with main app
Features:
- Send messages to notebook chat
- Get AI responses with source references
- Retrieve chat history
- Support for citations in responses
Tests:
- 14 unit tests for ChatService
- 11 integration tests for chat API
- 25/25 tests passing
Related: Sprint 3 - Chat Functionality
