feat: Enhance ticketing system with categories, templates, SLA tracking, and fix frontend integration

- Add ticket categories (billing, technical, feature_request, etc.) with type-specific options
- Add TicketTemplate and CannedResponse models for quick ticket creation
- Implement SLA tracking with due_at and first_response_at fields
- Add is_platform_admin and is_customer helper functions to fix permission checks
- Register models in Django admin with filters and fieldsets
- Enhance signals with error handling for WebSocket notifications
- Fix frontend API URLs for templates and canned responses
- Update PlatformSupport page to use real ticketing API
- Add comprehensive i18n translations for all ticket fields

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

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

frontend/src/layouts/BusinessLayout.tsx

@@ -7,6 +7,7 @@ import { Business, User } from '../types';
 import MasqueradeBanner from '../components/MasqueradeBanner';
 import OnboardingWizard from '../components/OnboardingWizard';
 import { useStopMasquerade } from '../hooks/useAuth';
+import { useNotificationWebSocket } from '../hooks/useNotificationWebSocket'; // Import the new hook
 import { MasqueradeStackEntry } from '../api/auth';
 import { useScrollToTop } from '../hooks/useScrollToTop';
 
@@ -176,6 +177,8 @@ const BusinessLayout: React.FC<BusinessLayoutProps> = ({ business, user, darkMod
     stopMasqueradeMutation.mutate();
   };
 
+  useNotificationWebSocket(); // Activate the notification WebSocket listener
+
   // Get the previous user from the stack (the one we'll return to)
   const previousUser = masqueradeStack.length > 0
     ? {