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/management/commands/dns_transfer_endpoint/catalog_zone_manager.py

@@ -3,8 +3,8 @@ import dns.zone
 import dns.rdatatype
 import dns.rdataclass
 from netbox_dns_bridge.utils import get_logger
-from netbox_dns.models import Zone as NBZone
-from netbox_dns_bridge.models import IntegerKeyValueSetting, CatalogZoneMemberIdentifier
+from netbox_dns.models import Zone as NBZone, View as NBView
+from netbox_dns_bridge.models import CatalogZone, CatalogZoneMemberIdentifier
 from uuid import uuid4
 from base64 import b32encode
 from django.db import transaction, close_old_connections, OperationalError
@@ -13,31 +13,32 @@ from django.db import transaction, close_old_connections, OperationalError
 LOGGER = get_logger(__name__)
 
 
-def increment_soa_serial() -> int:
+def increment_soa_serial(view: NBView) -> int:
     with transaction.atomic():
         try:
             (
                 soa_serial_obj,
                 _,
-            ) = IntegerKeyValueSetting.objects.select_for_update().get_or_create(
-                key="catalog-zone-soa-serial",
-                defaults={"value": 1},
+            ) = CatalogZone.objects.select_for_update().get_or_create(
+                view=view,
+                defaults={"soa_serial": 1},
             )
 
-            new_soa_serial = soa_serial_obj.value + 1
+            new_soa_serial = soa_serial_obj.soa_serial + 1
             if new_soa_serial > 0xFFFFFFFF:
                 LOGGER.warning(
-                    f"Catalog serial {soa_serial_obj.value} reached max — wrapping back to 1"
+                    f"Catalog serial {soa_serial_obj.soa_serial} reached max — wrapping back to 1"
                 )
                 new_soa_serial = 1
-            soa_serial_obj.value = new_soa_serial
+            soa_serial_obj.soa_serial = new_soa_serial
             soa_serial_obj.save()
             soa_serial_obj.refresh_from_db()
             LOGGER.debug(
-                f"Catalog zone SOA serial number is now {soa_serial_obj.value}"
+                f"Catalog zone SOA serial for view '{view.name}' "
+                f"is now {soa_serial_obj.soa_serial}"
             )
 
-            return soa_serial_obj.value
+            return soa_serial_obj.soa_serial
         except OperationalError as e:
             LOGGER.error(
                 f"ERROR: Failed to increment the Catalog Zone's SOA serial: {e}"
@@ -69,8 +70,11 @@ def create_zone(name, view_name) -> dns.zone.Zone:
             try:
                 catz_identifier = nb_zone.catz_identifier
             except NBZone.catz_identifier.RelatedObjectDoesNotExist:
+                catalog_zone = _get_or_create_catalog_zone(nb_zone.view)
                 catz_identifier = CatalogZoneMemberIdentifier.objects.create(
-                    zone=nb_zone, name=_generate_member_identifier()
+                    zone=nb_zone,
+                    name=_generate_member_identifier(),
+                    catalog_zone=catalog_zone,
                 )
 
             p_name = catz_identifier.name
@@ -100,7 +104,8 @@ def create_zone(name, view_name) -> dns.zone.Zone:
         zone_root_node = zone.find_node(origin, create=True)
 
         # SOA record
-        soa_rdataset = _create_soa_rdataset()
+        view = NBView.objects.get(name=view_name)
+        soa_rdataset = _create_soa_rdataset(view)
         zone_root_node.rdatasets.append(soa_rdataset)
 
         # NS record
@@ -126,23 +131,34 @@ def _generate_member_identifier() -> str:
     return b32encode(uuid4().bytes)[0:26].lower().decode("UTF-8")
 
 
+def _get_or_create_catalog_zone(view: NBView) -> CatalogZone:
+    catalog_zone, _ = CatalogZone.objects.get_or_create(
+        view=view, defaults={"soa_serial": 1}
+    )
+    return catalog_zone
+
+
 def update_member_identifier(zone: NBZone) -> None:
     try:
+        catalog_zone = _get_or_create_catalog_zone(zone.view)
         CatalogZoneMemberIdentifier.objects.update_or_create(
             zone=zone,
-            defaults={"name": _generate_member_identifier()},
+            defaults={
+                "name": _generate_member_identifier(),
+                "catalog_zone": catalog_zone,
+            },
         )
     except OperationalError as e:
         LOGGER.error(f"ERROR: Failed to update Catalog Zone member identifier: {e}")
         close_old_connections()
 
 
-def _create_soa_rdataset() -> dns.rdataset:
+def _create_soa_rdataset(view: NBView) -> dns.rdataset:
     try:
-        serial_obj, _ = IntegerKeyValueSetting.objects.get_or_create(
-            key="catalog-zone-soa-serial", defaults={"value": 1}
+        serial_obj, _ = CatalogZone.objects.get_or_create(
+            view=view, defaults={"soa_serial": 1}
         )
-        serial = serial_obj.value
+        serial = serial_obj.soa_serial
 
         # SOA Record components
         ttl = 0