� FIX: RAG系统导入和API集成修复 - Fixed RAG imports, updated API endpoints and frontend integration

Create New Assistant now switches to blank session instead of creating immediately

Only create session when user sends first message - no empty sessions

Add assistant attribution to messages

� MULTI-ASSISTANT SUPPORT: Label each message with assistant info

Add debug logs for Session click issue

� 修复预设system prompt显示在聊记录中的问题

add

Production ready build with modular backend