- Added API endpoints for prompt optimization:
* POST /prompt/sessions: Create a new prompt optimization session
* GET /prompt/sessions/{session_id}: Retrieve session message history
* POST /prompt/sessions/{session_id}/messages: Send message and get optimized prompt
* PUT /prompt/model: Create or update system prompt model configuration
- Added database models for prompt optimization:
* prompt_opt_session: Stores session metadata
* prompt_opt_session_history: Stores session message history
* prompt_opt_message: Stores user and assistant messages
* prompt_opt_model_config: Stores system prompt model configurations
- Updated service layer to handle message creation, prompt optimization, and variable parsing
- Added corresponding Pydantic schemas for request and response validation
