- Add expires_at field to ChatSession model with 2-hour default
- Sessions automatically expire after 2 hours of inactivity
- Active conversations extend session by 2 hours per message
- Add session expiration checks in chat views
- Create cleanup management command for expired sessions
- Add session status indicators in chat UI
- Fix null safety for existing sessions without expiration
🤖 Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>
