fix(code-review): resolve OpcUaServer-001 — UNS Area/Line rename refreshes folder DisplayName

A rename-only deploy produced an IsEmpty plan that short-circuited before MaterialiseHierarchy,
leaving the OPC UA folder DisplayName stale. AddressSpacePlanner now diffs UnsAreas/UnsLines by
stable id into a RenamedFolders set (counted in IsEmpty); the applier refreshes the folder in
place via a new UpdateFolderDisplayName on ISurgicalAddressSpaceSink (forwarded through
DeferredAddressSpaceSink so it is NOT inert on driver hosts; falls back to rebuild when the sink
is non-surgical). DeploymentArtifact byte-parity untouched (rename rides the existing Name
round-trip). No EF migration, no serialized wire/proto contract change. +13 OpcUaServer tests, Runtime rebuild test.

tests/Core/ZB.MOM.WW.OtOpcUa.Commons.Tests/OpcUa/DeferredAddressSpaceSinkTests.cs

@@ -90,6 +90,30 @@ public class DeferredAddressSpaceSinkTests
         surgical.UpdateCalled.ShouldBeTrue();
     }
 
+    [Fact]
+    public void UpdateFolderDisplayName_returns_false_for_non_surgical_inner()
+    {
+        // SpySink does NOT implement ISurgicalAddressSpaceSink.
+        var sink = new DeferredAddressSpaceSink();
+        sink.SetSink(new SpySink());
+
+        sink.UpdateFolderDisplayName("area-1", "Plant South").ShouldBeFalse();
+    }
+
+    [Fact]
+    public void UpdateFolderDisplayName_returns_true_for_surgical_inner()
+    {
+        // OpcUaServer-001: the deferred wrapper must forward the folder-rename capability to a surgical inner.
+        var surgical = new SpySurgicalSink();
+        var sink = new DeferredAddressSpaceSink();
+        sink.SetSink(surgical);
+
+        var result = sink.UpdateFolderDisplayName("area-1", "Plant South");
+
+        result.ShouldBeTrue();
+        surgical.FolderRenameCalled.ShouldBeTrue();
+    }
+
     // ---------- SetSink(null) reverts to null sink ----------
 
     [Fact]
@@ -137,6 +161,7 @@ public class DeferredAddressSpaceSinkTests
     private sealed class SpySurgicalSink : IOpcUaAddressSpaceSink, ISurgicalAddressSpaceSink
     {
         public bool UpdateCalled { get; private set; }
+        public bool FolderRenameCalled { get; private set; }
 
         public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime sourceTimestampUtc) { }
         public void WriteAlarmCondition(string alarmNodeId, AlarmConditionSnapshot state, DateTime sourceTimestampUtc) { }
@@ -150,5 +175,11 @@ public class DeferredAddressSpaceSinkTests
             UpdateCalled = true;
             return true;
         }
+
+        public bool UpdateFolderDisplayName(string folderNodeId, string displayName)
+        {
+            FolderRenameCalled = true;
+            return true;
+        }
     }
 }