feat: ticketing system with technical/sales roles and department routing

Backend:
- Added TECHNICAL and SALES roles to UserRole enum
- Added TicketDepartment, TicketStatus, TicketPriority enums
- Created Ticket and TicketMessage entities with relationships
- Created TicketsModule with full CRUD service and controller
- Ticket routing: users create tickets to technical/sales departments
- Staff reply updates status (answered), user reply sets waiting
- Role-based access: technical staff sees technical tickets, sales sees sales tickets
- Admin sees all tickets with stats (total, open, avg response time)
- Updated access control: technical role has admin-level access (except role change)
- Sales role can view users and handle sales tickets
- Clusters controller: technical role can manage clusters/pools
- Users controller: technical/sales can view users, only admin changes roles

Frontend:
- New user ticket pages: list (with create form) + detail (chat-style messages)
- Staff ticket panel: filtered by department with status filters
- Admin all-tickets page with statistics dashboard and department/status filters
- Updated sidebar: role-based nav items (admin/technical/sales sections)
- Role badges in header for technical (blue) and sales (green)
- Admin users page: new roles in dropdowns, role change restricted to admin only
- Deploy page: technical role gets cluster selection access like admin

frontend/src/app/dashboard/deploy/page.tsx

@@ -13,7 +13,7 @@ const steps = ['Basic Info', 'Runtime & Database', 'Resources', 'Review'];
 export default function DeployPage() {
   const router = useRouter();
   const user = useAuthStore((s) => s.user);
-  const isAdmin = user?.role === 'admin';
+  const isAdmin = user?.role === 'admin' || user?.role === 'technical';
   const [step, setStep] = useState(0);
   const [form, setForm] = useState<CreateApplicationDto>({
     name: '',