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

backend/src/common/enums.ts

@@ -3,6 +3,26 @@
 export enum UserRole {
   USER = 'user',
   ADMIN = 'admin',
+  TECHNICAL = 'technical',
+  SALES = 'sales',
+}
+
+export enum TicketDepartment {
+  TECHNICAL = 'technical',
+  SALES = 'sales',
+}
+
+export enum TicketStatus {
+  OPEN = 'open',
+  ANSWERED = 'answered',
+  WAITING = 'waiting',       // waiting for staff reply
+  CLOSED = 'closed',
+}
+
+export enum TicketPriority {
+  LOW = 'low',
+  MEDIUM = 'medium',
+  HIGH = 'high',
 }
 
 export enum AppRuntime {