feat(api): add PATCH /chat/sessions/{session_id} to rename chat sessions

[sachin-mahato25]

Closes #434

Summary

Added PATCH /chat/sessions/{session_id} route to support renaming chat sessions by the authenticated user.

Changes

• Added PATCH /chat/sessions/{session_id} endpoint in backend/app/routes/chat.py

Requirements Completed

• ✅ Created PATCH /chat/sessions/{session_id} route
• ✅ Updates chat session title in the database
• ✅ Authorization check ensures only the session owner can rename it (filters by both session_id and user.id)

Testing

• Returns 200 with updated session when valid title is provided by the owner
• Returns 404 if session does not exist or belongs to another user

[sachin-mahato25]

Hey @param20h! I've worked on this issue and opened a PR that implements the PATCH /chat/sessions/{session_id} route.

Changes made:

• Added PATCH /chat/sessions/{session_id} endpoint in backend/app/routes/chat.py
• Updates the session title in the database
• Authorization check ensures only the session owner can rename it

Please review when you get a chance. Happy to make any changes if needed! 🙌