Replace global IntegerKeyValueSetting with per-view CatalogZone model

Track the catalog zone SOA serial per view instead of a single global value.
The new CatalogZone model has a 1:1 FK to netbox_dns.models.View and its own
soa_serial field; each view's catalog zone now increments independently. The
existing global serial is preserved during migration by copying it into every
view's new CatalogZone row.

Change CatalogZoneMemberIdentifier.name from globally unique to unique per
catalog zone (UniqueConstraint(name, catalog_zone)) and add a catalog_zone FK
to enforce it.

Remove the dns-settings management command, which was a generic interface over
the now-removed IntegerKeyValueSetting model.

Increment both catalog zone serials when a zone moves between views: the old
view's catalog zone loses a member and the new view's gains one, so both must
be bumped. Also refresh the member identifier's catalog_zone FK on a view move
so it does not go stale. The pre_save handler now captures _old_view_id and the
post_save handler detects view changes, increments the old view's serial inside
on_commit (before the new view's), and re-creates the identifier.

AI generated, code manually verified.

netbox_dns_bridge/signals/netbox_dns_zones.py

@@ -3,7 +3,7 @@ from django.dispatch import receiver
 from django.db import transaction
 from django.conf import settings
 from netbox.context import current_request
-from netbox_dns.models import Zone
+from netbox_dns.models import Zone, View
 from netbox_dns_bridge.management.commands.dns_transfer_endpoint import catalog_zone_manager as catzm
 from . import notify_handler
 
@@ -14,15 +14,18 @@ def zone_pre_save(sender, instance, **kwargs):
     zone = instance
     if zone.pk:
         try:
-            old = sender.objects.only("name", "soa_serial").get(pk=zone.pk)
+            old = sender.objects.only("name", "soa_serial", "view_id").get(pk=zone.pk)
             zone._old_name = old.name
             zone._old_soa_serial = old.soa_serial
+            zone._old_view_id = old.view_id
         except sender.DoesNotExist:
             zone._old_name = None
             zone._old_soa_serial = None
+            zone._old_view_id = None
     else:
         zone._old_name = None
         zone._old_soa_serial = None
+        zone._old_view_id = None
 
 
 @receiver(post_save, sender=Zone)
@@ -32,6 +35,8 @@ def zone_post_save(sender, instance, created, **kwargs):
     # Quit if this is not the first signal in this session for this zone.
     try:
         request = current_request.get()
+        if request is None:
+            raise LookupError
         handled_zones = getattr(request, "_handled_zones", set())
         if zone.pk in handled_zones:
             return
@@ -46,9 +51,25 @@ def zone_post_save(sender, instance, created, **kwargs):
     new_soa_serial = getattr(zone, "soa_serial", None)
     soa_serial_changed = created or (old_soa_serial != new_soa_serial)
 
+    # Detect whether the zone moved between views. When it does, the old
+    # view's catalog zone loses a member and the new view's gains one, so
+    # both serials must be incremented.
+    old_view_id = getattr(zone, "_old_view_id", None)
+    view_changed = (
+        not created
+        and old_view_id is not None
+        and old_view_id != zone.view_id
+    )
+
     # On commit, increment soa serial and if notify is enabled, schedule bg job.
     def _on_commit():
-        catzm.increment_soa_serial()
+        if view_changed:
+            try:
+                old_view = View.objects.get(pk=old_view_id)
+                catzm.increment_soa_serial(old_view)
+            except View.DoesNotExist:
+                pass
+        catzm.increment_soa_serial(zone.view)
 
         if SETTINGS.get("notify_clients", False):
             notify_handler.schedule_client_notify(zone)
@@ -64,16 +85,18 @@ def zone_post_save(sender, instance, created, **kwargs):
         # If zone was created, create catz member identifier record for this zone.
         catzm.update_member_identifier(zone)
     else:
-        # Check if zone name has changed and change the catz member identifier if so.
+        # Re-create the catz member identifier when the zone name or its view
+        # changed. A view move leaves the identifier pointing at the wrong
+        # catalog zone, so it must be refreshed.
         old_name = getattr(zone, "_old_name", None)
-        if old_name and zone.name != old_name:
+        if (old_name and zone.name != old_name) or view_changed:
             catzm.update_member_identifier(zone)
 
 
 @receiver(post_delete, sender=Zone)
 def zone_post_delete(sender, instance, **kwargs):
     def _on_commit():
-        catzm.increment_soa_serial()
+        catzm.increment_soa_serial(instance.view)
 
     transaction.on_commit(_on_commit)