fix(opcua): equipment-tag planner diff + folder-scoped NodeIds (review findings)

Two bundle-review fixes + idempotency coverage:
- CRITICAL: the planner ignored EquipmentTags, so an incremental deploy changing only
  equipment tags produced an empty plan and HandleRebuild short-circuited before
  materialising them. Add TagId to EquipmentTagPlan + Added/Removed/ChangedEquipmentTags
  to Phase7Plan (diffed by TagId, in IsEmpty, driving Apply's needsRebuild) — mirroring
  the GalaxyTags treatment.
- IMPORTANT: equipment variable NodeId was the raw driver FullName, which collides across
  identical machines (e.g. two PLCs both exposing register 40001) — the second variable
  was silently dropped. NodeId is now folder-scoped (parent/Name); FullName stays on
  EquipmentTagPlan for the later values-routing milestone.
- Task 4: SDK-backed idempotency test (double-apply -> single variable); restart-safety
  confirmed (RestoreApplied reuses the same RebuildAddressSpace -> HandleRebuild path).
- Minor: align composer equipment-tag sort with the artifact decoder (coalesce FolderPath).

tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.Tests/Phase7PlannerTests.cs

@@ -30,6 +30,31 @@ public sealed class Phase7PlannerTests
         plan.IsEmpty.ShouldBeTrue();
     }
 
+    /// <summary>Verifies an equipment-tag-only delta (no equipment/driver/alarm/galaxy change)
+    /// yields a NON-empty plan, so OpcUaPublishActor.HandleRebuild does not short-circuit at the
+    /// IsEmpty gate before materialising the new equipment variables.</summary>
+    [Fact]
+    public void Equipment_tag_only_change_yields_non_empty_plan_with_added_tag()
+    {
+        var prev = new Phase7CompositionResult(
+            Array.Empty<EquipmentNode>(), Array.Empty<DriverInstancePlan>(), Array.Empty<ScriptedAlarmPlan>());
+        var next = new Phase7CompositionResult(
+            Array.Empty<EquipmentNode>(), Array.Empty<DriverInstancePlan>(), Array.Empty<ScriptedAlarmPlan>())
+        {
+            EquipmentTags = new[]
+            {
+                new EquipmentTagPlan("tag-1", "eq-1", "drv", FolderPath: "", Name: "Speed", DataType: "Float", FullName: "40001"),
+            },
+        };
+
+        var plan = Phase7Planner.Compute(prev, next);
+
+        plan.IsEmpty.ShouldBeFalse();
+        plan.AddedEquipmentTags.Single().TagId.ShouldBe("tag-1");
+        plan.RemovedEquipmentTags.ShouldBeEmpty();
+        plan.ChangedEquipmentTags.ShouldBeEmpty();
+    }
+
     /// <summary>Verifies that new equipment goes to the AddedEquipment list.</summary>
     [Fact]
     public void New_equipment_goes_to_AddedEquipment()