feat(otopcua): OpcUaPublishActor handles discovered-node materialisation

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

@@ -56,6 +56,13 @@ public sealed class OpcUaPublishActor : ReceiveActor, IWithTimers
     ///     fall back to the latest sealed deployment (lags a not-yet-sealed apply by one revision).
     /// </summary>
     public sealed record RebuildAddressSpace(CorrelationId Correlation, DeploymentId? DeploymentId = null);
+
+    /// <summary>Inject driver-discovered nodes (FixedTree) under an equipment at runtime (post-connect).</summary>
+    public sealed record MaterialiseDiscoveredNodes(
+        string EquipmentRootNodeId,
+        IReadOnlyList<DiscoveredFolder> Folders,
+        IReadOnlyList<DiscoveredVariable> Variables);
+
     public sealed record ServiceLevelChanged(byte ServiceLevel);
 
     private readonly IOpcUaAddressSpaceSink _sink;
@@ -217,6 +224,7 @@ public sealed class OpcUaPublishActor : ReceiveActor, IWithTimers
         Receive<AttributeValueUpdate>(HandleAttributeUpdate);
         Receive<AlarmStateUpdate>(HandleAlarmUpdate);
         Receive<RebuildAddressSpace>(HandleRebuild);
+        Receive<MaterialiseDiscoveredNodes>(HandleMaterialiseDiscovered);
         Receive<ServiceLevelChanged>(HandleServiceLevelChanged);
         Receive<RedundancyStateChanged>(HandleRedundancyStateChanged);
         Receive<DbHealthProbeActor.DbHealthStatus>(HandleDbHealthStatus);
@@ -390,6 +398,12 @@ public sealed class OpcUaPublishActor : ReceiveActor, IWithTimers
         }
     }
 
+    /// <summary>Forwards driver-discovered (FixedTree) nodes to the applier so they are injected under
+    /// the equipment at runtime. No-op when no applier is wired (dev/Mac/legacy seam), matching the
+    /// optional-applier tolerance of <see cref="HandleRebuild"/>.</summary>
+    private void HandleMaterialiseDiscovered(MaterialiseDiscoveredNodes msg)
+        => _applier?.MaterialiseDiscoveredNodes(msg.EquipmentRootNodeId, msg.Folders, msg.Variables);
+
     private void HandleServiceLevelChanged(ServiceLevelChanged msg)
     {
         // Always publish the FIRST computed level, even if it equals the byte-default 0. Otherwise a