feat: unanswered ticket badges, dashboard counts, cross-department ticket creation

- Add /tickets/unanswered-counts API endpoint for staff/admin
- Show red badge with unanswered count on sidebar nav (staff tickets, admin tickets)
- Add summary cards (unanswered/answered/total) to staff tickets page
- Highlight unanswered count in admin tickets stats cards
- Staff can create tickets to OTHER departments only (not their own)
- Frontend hides own department from ticket creation dropdown
- Sidebar badges auto-refresh every 30 seconds

backend/src/tickets/tickets.service.ts

@@ -119,6 +119,19 @@ export class TicketsService {
     await this.ticketsRepo.update(ticketId, data);
   }
 
+  // ─── Unanswered ticket counts ───
+  async getUnansweredCounts(): Promise<{ technical: number; sales: number; total: number }> {
+    const unanswered = await this.ticketsRepo.find({
+      where: [
+        { status: TicketStatus.OPEN },
+        { status: TicketStatus.WAITING },
+      ],
+    });
+    const technical = unanswered.filter((t) => t.department === TicketDepartment.TECHNICAL).length;
+    const sales = unanswered.filter((t) => t.department === TicketDepartment.SALES).length;
+    return { technical, sales, total: technical + sales };
+  }
+
   // ─── Staff: List department tickets ───
   async findByDepartment(department: TicketDepartment, status?: TicketStatus): Promise<Ticket[]> {
     const where: any = { department };