feat: Add real-time ticket updates via WebSocket and staff permission control

WebSocket Updates:
- Create useTicketWebSocket hook for real-time ticket list updates
- Hook invalidates React Query cache when tickets are created/updated
- Shows toast notifications for new tickets and comments
- Auto-reconnect with exponential backoff

Staff Permissions:
- Add can_access_tickets() method to User model
- Owners and managers always have ticket access
- Staff members need explicit can_access_tickets permission
- Update Sidebar to conditionally show Tickets menu based on permission
- Add can_access_tickets to API user response

Backend Updates:
- Update ticket signals to broadcast updates to all relevant users
- Check ticket access permission in views

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

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

frontend/src/types.ts

@@ -88,6 +88,9 @@ export interface User {
   timezone?: string;
   locale?: string;
   notification_preferences?: NotificationPreferences;
+  can_invite_staff?: boolean;
+  can_access_tickets?: boolean;
+  permissions?: Record<string, boolean>;
 }
 
 export type ResourceType = 'STAFF' | 'ROOM' | 'EQUIPMENT';