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/App.tsx

@@ -55,7 +55,7 @@ import VerifyEmail from './pages/VerifyEmail';
 import EmailVerificationRequired from './pages/EmailVerificationRequired';
 import AcceptInvitePage from './pages/AcceptInvitePage';
 import TenantOnboardPage from './pages/TenantOnboardPage';
-import TicketsPage from './pages/TicketsPage'; // Import TicketsPage
+import Tickets from './pages/Tickets'; // Import Tickets page
 import { Toaster } from 'react-hot-toast'; // Import Toaster for notifications
 
 const queryClient = new QueryClient({
@@ -469,7 +469,7 @@ const AppContent: React.FC = () => {
             element={user.role === 'resource' ? <ResourceDashboard /> : <Dashboard />}
           />
           <Route path="/scheduler" element={<Scheduler />} />
-          <Route path="/tickets" element={<TicketsPage />} />
+          <Route path="/tickets" element={<Tickets />} />
           <Route
             path="/customers"
             element={