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/tickets/entities/ticket-message.entity.ts

@@ -0,0 +1,40 @@
+import {
+  Entity,
+  PrimaryGeneratedColumn,
+  Column,
+  CreateDateColumn,
+  ManyToOne,
+  JoinColumn,
+} from 'typeorm';
+import { Ticket } from './ticket.entity';
+import { User } from '../../users/entities/user.entity';
+import { UserRole } from '../../common/enums';
+
+@Entity('ticket_messages')
+export class TicketMessage {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column({ type: 'text' })
+  message: string;
+
+  @Column()
+  ticketId: string;
+
+  @ManyToOne(() => Ticket, (ticket) => ticket.messages, { onDelete: 'CASCADE' })
+  @JoinColumn({ name: 'ticketId' })
+  ticket: Ticket;
+
+  @Column()
+  senderId: string;
+
+  @ManyToOne(() => User, { onDelete: 'CASCADE' })
+  @JoinColumn({ name: 'senderId' })
+  sender: User;
+
+  @Column({ type: 'enum', enum: UserRole })
+  senderRole: UserRole;
+
+  @CreateDateColumn()
+  createdAt: Date;
+}

backend/src/tickets/entities/ticket.entity.ts

@@ -0,0 +1,50 @@
+import {
+  Entity,
+  PrimaryGeneratedColumn,
+  Column,
+  CreateDateColumn,
+  UpdateDateColumn,
+  ManyToOne,
+  OneToMany,
+  JoinColumn,
+} from 'typeorm';
+import { TicketDepartment, TicketStatus, TicketPriority } from '../../common/enums';
+import { User } from '../../users/entities/user.entity';
+import { TicketMessage } from './ticket-message.entity';
+
+@Entity('tickets')
+export class Ticket {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column()
+  subject: string;
+
+  @Column({ type: 'enum', enum: TicketDepartment })
+  department: TicketDepartment;
+
+  @Column({ type: 'enum', enum: TicketStatus, default: TicketStatus.OPEN })
+  status: TicketStatus;
+
+  @Column({ type: 'enum', enum: TicketPriority, default: TicketPriority.MEDIUM })
+  priority: TicketPriority;
+
+  @Column()
+  userId: string;
+
+  @ManyToOne(() => User, { onDelete: 'CASCADE' })
+  @JoinColumn({ name: 'userId' })
+  user: User;
+
+  @OneToMany(() => TicketMessage, (msg) => msg.ticket, { cascade: true })
+  messages: TicketMessage[];
+
+  @CreateDateColumn()
+  createdAt: Date;
+
+  @UpdateDateColumn()
+  updatedAt: Date;
+
+  @Column({ type: 'timestamp', nullable: true })
+  closedAt: Date;
+}