Closes #21016: Add missing MPTT tree indexes (#21432)

Upgrade django-mptt to 0.18.0 and add empty indexes tuple to MPTT model
Meta classes. The empty tuple triggers Django's migration detection for
indexes that django-mptt adds dynamically (see
django-mptt/django-mptt#682). We cannot define the indexes explicitly
because the MPTT fields don't exist when the Meta class is evaluated.

Affected models: Region, SiteGroup, Location, DeviceRole, Platform,
ModuleBay, InventoryItem, InventoryItemTemplate, TenantGroup,
ContactGroup, WirelessLANGroup

netbox/wireless/migrations/0018_add_mptt_tree_indexes.py

@@ -0,0 +1,19 @@
+# Generated by Django 5.2.10 on 2026-02-13 13:36
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('extras', '0134_owner'),
+        ('users', '0015_owner'),
+        ('wireless', '0017_gfk_indexes'),
+    ]
+
+    operations = [
+        migrations.AddIndex(
+            model_name='wirelesslangroup',
+            index=models.Index(fields=['tree_id', 'lft'], name='wireless_wirelesslangroup_fbcd'),
+        ),
+    ]

netbox/wireless/models.py

@@ -63,6 +63,9 @@ class WirelessLANGroup(NestedGroupModel):
 
     class Meta:
         ordering = ('name', 'pk')
+        # Empty tuple triggers Django migration detection for MPTT indexes
+        # (see #21016, django-mptt/django-mptt#682)
+        indexes = ()
         constraints = (
             models.UniqueConstraint(
                 fields=('parent', 'name'),