Add conversation history management and API endpoints

- Introduce new database models for conversation sessions, messages, and artifacts to support conversation history tracking.
- Implement API routes for listing conversations and retrieving detailed conversation data, enhancing user interaction with historical records.
- Add a conversation recorder service to persist conversation messages in real-time without disrupting ongoing calls.
- Update the frontend to display conversation history, including filtering and sorting options, improving user experience.
- Enhance the pipeline to integrate conversation history recording seamlessly during interactions.

backend/routes/voice_webrtc.py

@@ -120,7 +120,13 @@ async def _handle_offer(websocket, payload, peers):
             video_in_enabled=vision_enabled,
         )
         asyncio.create_task(
-            run_pipeline(transport, cfg, vision_enabled=vision_enabled)
+            run_pipeline(
+                transport,
+                cfg,
+                vision_enabled=vision_enabled,
+                assistant_id=offer.assistant_id,
+                channel="webrtc",
+            )
         )
 
     answer = pc.get_answer()