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/types/index.ts

@@ -3,7 +3,7 @@ export interface User {
   email: string;
   firstName: string;
   lastName: string;
-  role: 'user' | 'admin';
+  role: 'user' | 'admin' | 'technical' | 'sales';
   isActive: boolean;
   namespace?: string;
   createdAt: string;
@@ -181,3 +181,47 @@ export interface ClusterResources {
   nodeCount: number;
   appCount: number;
 }
+
+// ─── Ticket types ───────────────────────────────────
+
+export type TicketDepartment = 'technical' | 'sales';
+export type TicketStatus = 'open' | 'answered' | 'waiting' | 'closed';
+export type TicketPriority = 'low' | 'medium' | 'high';
+
+export interface Ticket {
+  id: string;
+  subject: string;
+  department: TicketDepartment;
+  status: TicketStatus;
+  priority: TicketPriority;
+  userId: string;
+  user?: User;
+  messages?: TicketMessageType[];
+  createdAt: string;
+  updatedAt: string;
+  closedAt?: string;
+}
+
+export interface TicketMessageType {
+  id: string;
+  message: string;
+  ticketId: string;
+  senderId: string;
+  senderRole: 'user' | 'admin' | 'technical' | 'sales';
+  sender?: User;
+  createdAt: string;
+}
+
+export interface CreateTicketDto {
+  subject: string;
+  department: TicketDepartment;
+  priority?: TicketPriority;
+  message: string;
+}
+
+export interface TicketStats {
+  totalTickets: number;
+  openTickets: number;
+  avgResponseTimeMinutes: number;
+  byDepartment: Record<string, { total: number; open: number; answered: number; closed: number }>;
+}