Add service-point routing so call-next cannot steal assigned tickets.

Counters gain destination/staff metadata; tickets can be pre-assigned to a
service point with assigned_only queues for healthcare while shared_pool
preserves generic bank/government behavior. Display and announcements expose
ticket, staff, and destination clearly for Care and public boards.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/Models/Department.php

@@ -14,7 +14,7 @@ class Department extends Model
     protected $table = 'queue_departments';
 
     protected $fillable = [
-        'owner_ref', 'branch_id', 'name', 'type', 'is_active',
+        'owner_ref', 'branch_id', 'name', 'type', 'external_key', 'is_active',
     ];
 
     protected function casts(): array
@@ -26,4 +26,14 @@ class Department extends Model
     {
         return $this->belongsTo(Branch::class, 'branch_id');
     }
+
+    public function counters(): \Illuminate\Database\Eloquent\Relations\HasMany
+    {
+        return $this->hasMany(Counter::class, 'department_id');
+    }
+
+    public function serviceQueues(): \Illuminate\Database\Eloquent\Relations\HasMany
+    {
+        return $this->hasMany(ServiceQueue::class, 'department_id');
+    }
 }