feat(comm): route BrowseOpcUaNodeCommand from central to site DCL manager

Wires the OPC UA Tag Browser cross-cluster path: central UI Asks via
CommunicationService.BrowseOpcUaNodeAsync -> ClusterClient -> site
SiteCommunicationActor -> /user/dcl-manager (Task 10 handler).

Uses ActorSelection.Tell(msg, Sender) since DataConnectionManagerActor
is not a child of DeploymentManagerActor and ActorSelection has no
Forward() helper; preserving Sender keeps the BrowseOpcUaNodeResult
routing back to the original Ask.

Integration test deferred: tests/ZB.MOM.WW.ScadaBridge.IntegrationTests
has no ClusterFixture (only ScadaBridgeWebApplicationFactory, which
does not expose a Communication service nor a seeded site OPC UA
connection). Round-trip will be exercised manually under Task 19.

src/ZB.MOM.WW.ScadaBridge.Communication/Actors/SiteCommunicationActor.cs

@@ -10,6 +10,7 @@ using ZB.MOM.WW.ScadaBridge.Commons.Messages.Health;
 using ZB.MOM.WW.ScadaBridge.Commons.Messages.InboundApi;
 using ZB.MOM.WW.ScadaBridge.Commons.Messages.Integration;
 using ZB.MOM.WW.ScadaBridge.Commons.Messages.Lifecycle;
+using ZB.MOM.WW.ScadaBridge.Commons.Messages.Management;
 using ZB.MOM.WW.ScadaBridge.Commons.Messages.Notification;
 using ZB.MOM.WW.ScadaBridge.Commons.Messages.RemoteQuery;
 
@@ -144,6 +145,24 @@ public class SiteCommunicationActor : ReceiveActor, IWithTimers
         Receive<RouteToGetAttributesRequest>(msg => _deploymentManagerProxy.Forward(msg));
         Receive<RouteToSetAttributesRequest>(msg => _deploymentManagerProxy.Forward(msg));
 
+        // OPC UA Tag Browser (interactive design-time query) — forward to the
+        // site-local Data Connection Manager actor, which owns the in-memory
+        // map of live data-connection adapters keyed by ConnectionName and
+        // executes the browse against the appropriate OPC UA client. The
+        // manager is not a child of DeploymentManagerActor, so we route via
+        // ActorSelection rather than the _deploymentManagerProxy field; the
+        // path matches the registration in AkkaHostedService. ActorSelection
+        // has no Forward() helper, so we Tell with the original Sender so the
+        // BrowseOpcUaNodeResult routes straight back to the central UI's Ask
+        // (via the CentralCommunicationActor sender chain), not to us.
+        Receive<BrowseOpcUaNodeCommand>(msg =>
+        {
+            _log.Debug(
+                "Routing BrowseOpcUaNodeCommand for connection '{0}' to DataConnectionManager",
+                msg.ConnectionName);
+            Context.ActorSelection("/user/dcl-manager").Tell(msg, Sender);
+        });
+
         // Pattern 7: Remote Queries
         Receive<EventLogQueryRequest>(msg =>
         {