feat(opcua): #85 UNS Area/Line/Equipment folder hierarchy in SDK

Phase7Composer now carries UnsAreaProjection + UnsLineProjection lists so
the applier can materialise the full UNS topology in the OPC UA address
space. New IOpcUaAddressSpaceSink.EnsureFolder(folderNodeId, parentNodeId,
displayName) seam (no-op default, recorded in tests, forwarded by
DeferredAddressSpaceSink, implemented by SdkAddressSpaceSink). The SDK-
side OtOpcUaNodeManager gains an EnsureFolder API that creates
FolderState nodes with proper parent linkage; RebuildAddressSpace now
clears folders too so re-applies don't accumulate stale topology.

Phase7Applier.MaterialiseHierarchy walks composition.UnsAreas →
composition.UnsLines → composition.EquipmentNodes, calling EnsureFolder
with the correct parent at each level. Idempotent — calling twice with
the same composition is a no-op. OpcUaPublishActor.HandleRebuild invokes
it after Phase7Applier.Apply so OPC UA clients browsing the server now
see Area/Line/Equipment as proper folders rather than flat tag ids.

DeploymentArtifact.ParseComposition reads UnsAreas + UnsLines from the
JSON snapshot the ControlPlane emits, populating the new fields when
present.

Phase7Composer.Compose now accepts UnsAreas + UnsLines; a 3-arg overload
preserves the old signature for legacy callers + existing tests. The
Phase7CompositionResult convenience ctor likewise keeps the planner
tests working without UNS data.

3 new hierarchy tests (pure unit + boot-verify against a real
OtOpcUaSdkServer); OpcUaServer suite is 48/48 green (was 45, +3),
Runtime 74/74 unchanged.

Closes #85.

src/Server/ZB.MOM.WW.OtOpcUa.Runtime/OpcUa/OpcUaPublishActor.cs

@@ -185,6 +185,12 @@ public sealed class OpcUaPublishActor : ReceiveActor
 
             var outcome = _applier.Apply(plan);
             _lastApplied = composition;
+
+            // #85 — after the plan diff lands, rebuild the UNS folder hierarchy so OPC UA
+            // clients see Area/Line/Equipment as proper folders. Idempotent; Phase7Applier
+            // skips folders that already exist with the same node id.
+            _applier.MaterialiseHierarchy(composition);
+
             OtOpcUaTelemetry.OpcUaSinkWrite.Add(1, new KeyValuePair<string, object?>("kind", "rebuild"));
             _log.Info("OpcUaPublish: applied rebuild (correlation={Correlation}, added={Added}, removed={Removed}, changed={Changed}, rebuild={Rebuild})",
                 msg.Correlation, outcome.AddedNodes, outcome.RemovedNodes, outcome.ChangedNodes, outcome.RebuildCalled);