feat: Add Chat UX improvements with notifications and @mention support

- Add ActionBar component with expandable toolbar for mobile
- Add @mention functionality with autocomplete dropdown
- Add browser notification system (push, sound, vibration)
- Add NotificationSettings modal for user preferences
- Add mention badges on room list cards
- Add ReportPreview with Markdown rendering and copy/download
- Add message copy functionality with hover actions
- Add backend mentions field to messages with Alembic migration
- Add lots field to rooms, remove templates
- Optimize WebSocket database session handling
- Various UX polish (animations, accessibility)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/modules/chat_room/__init__.py

@@ -3,17 +3,14 @@
 Provides functionality for creating and managing incident response chat rooms
 """
 from app.modules.chat_room.router import router
-from app.modules.chat_room.models import IncidentRoom, RoomMember, RoomTemplate
+from app.modules.chat_room.models import IncidentRoom, RoomMember
 from app.modules.chat_room.services.room_service import room_service
 from app.modules.chat_room.services.membership_service import membership_service
-from app.modules.chat_room.services.template_service import template_service
 
 __all__ = [
     "router",
     "IncidentRoom",
     "RoomMember",
-    "RoomTemplate",
     "room_service",
     "membership_service",
-    "template_service"
 ]