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/i18n/locales/en.json

@@ -83,18 +83,23 @@
   "tickets": {
     "title": "Support Tickets",
     "description": "Manage your support requests and inquiries.",
+    "descriptionOwner": "Manage support tickets for your business",
+    "descriptionStaff": "View and create support tickets",
     "newTicket": "New Ticket",
     "errorLoading": "Error loading tickets",
     "subject": "Subject",
+    "description": "Description",
     "status": "Status",
     "priority": "Priority",
     "category": "Category",
+    "ticketType": "Ticket Type",
     "assignee": "Assignee",
+    "assignedTo": "Assigned to",
     "createdAt": "Created At",
     "unassigned": "Unassigned",
-    "noTicketsFound": "No tickets found.",
+    "noTicketsFound": "No tickets found",
+    "noTicketsInStatus": "No tickets with this status",
     "ticketDetails": "Ticket Details",
-    "categoryPlaceholder": "e.g., Billing, Technical, Feature Request",
     "createTicket": "Create Ticket",
     "updateTicket": "Update Ticket",
     "comments": "Comments",
@@ -103,14 +108,47 @@
     "addCommentPlaceholder": "Add a comment...",
     "internalComment": "Internal Comment",
     "postComment": "Post Comment",
-    "priority.low": "Low",
-    "priority.medium": "Medium",
-    "priority.high": "High",
-    "priority.urgent": "Urgent",
-    "status.open": "Open",
-    "status.in_progress": "In Progress",
-    "status.resolved": "Resolved",
-    "status.closed": "Closed"
+    "tabs": {
+      "all": "All",
+      "open": "Open",
+      "inProgress": "In Progress",
+      "awaitingResponse": "Awaiting Response",
+      "resolved": "Resolved",
+      "closed": "Closed"
+    },
+    "priorities": {
+      "low": "Low",
+      "medium": "Medium",
+      "high": "High",
+      "urgent": "Urgent"
+    },
+    "statuses": {
+      "open": "Open",
+      "in_progress": "In Progress",
+      "awaiting_response": "Awaiting Response",
+      "resolved": "Resolved",
+      "closed": "Closed"
+    },
+    "types": {
+      "platform": "Platform Support",
+      "customer": "Customer Inquiry",
+      "staff_request": "Staff Request",
+      "internal": "Internal"
+    },
+    "categories": {
+      "billing": "Billing & Payments",
+      "technical": "Technical Issue",
+      "feature_request": "Feature Request",
+      "account": "Account & Settings",
+      "appointment": "Appointment Issue",
+      "refund": "Refund Request",
+      "complaint": "Complaint",
+      "general_inquiry": "General Inquiry",
+      "time_off": "Time Off Request",
+      "schedule_change": "Schedule Change",
+      "equipment": "Equipment Issue",
+      "other": "Other"
+    }
   },
   "dashboard": {
     "title": "Dashboard",