test(v3): migrate OpcUaServer.Tests + Host.IntegrationTests to v3 dark address space

Migrate the server composer/applier + 2-node harness tests off the retired
Namespace/NamespaceKind + equipment→driver/device binding schema onto the v3
greenfield shape (raw-only Tag; DriverInstance-RawFolderId; equipment via UnsLine).

OpcUaServer.Tests (134 build errors -> green, 335 pass / 4 skip):
- LIVE (migrated, passing): VirtualTag-historize + ScriptedAlarm composition,
  composer purity/hierarchy, applier MaterialiseHierarchy + MaterialiseEquipmentTags
  idempotency (hand-fed applier, not dark).
- SKIP dark-until-Batch-4: {{equip}} token expansion, applier equipment-namespace
  E2E (equipment-tag variable materialization).
- RETIRE-with-comment / skip: alias-tag (Tag.EquipmentId binding gone) + device-host
  equipment binding (architecturally removed).
- Add local DarkAddressSpaceReasons Skip-reason constants (mirrors Runtime.Tests).

Host.IntegrationTests (green, in-memory): drop deleted-Namespace seeds from
MultiClusterScoping + DriverReconnect; reshape EquipmentNamespaceMaterialization to
assert the DARK contract (folder nodes decode, EquipmentTags empty despite a seeded
v3 raw tag) with the full raw-tag->EquipmentTag materialization kept as a
Batch-4-pending Skip.

Tests-only; no src/ changes.

tests/Server/ZB.MOM.WW.OtOpcUa.Host.IntegrationTests/DriverReconnectE2eTests.cs

@@ -225,14 +225,7 @@ public sealed class DriverReconnectE2eTests
             CreatedBy = "test",
         });
 
-        db.Namespaces.Add(new Namespace
-        {
-            NamespaceId = "RECONNECT-E2E-equipment",
-            ClusterId = ClusterId,
-            Kind = NamespaceKind.Equipment,
-            NamespaceUri = "urn:zb:reconnect-e2e:equipment",
-        });
-
+        // v3: the Namespace entity is deleted (DriverInstance no longer binds a Namespace).
         db.ClusterNodes.Add(new ClusterNode
         {
             NodeId = harness.NodeANodeId,
@@ -258,7 +251,6 @@ public sealed class DriverReconnectE2eTests
         {
             DriverInstanceId = DriverId,
             ClusterId = ClusterId,
-            NamespaceId = "RECONNECT-E2E-equipment",
             Name = DriverId,
             DriverType = "Modbus",
             Enabled = true,