feat(dcl+ui): rename BrowseOpcUaNode -> ConnectionName-keyed; implement site handler + dialog failure mapping

- BrowseOpcUaNodeCommand: int DataConnectionId -> string ConnectionName
  (site DataConnectionManagerActor indexes children by name; CentralUI
  already has the connection name in scope via the dropdown — no extra
  plumbing across the trust boundary).
- IOpcUaBrowseService / OpcUaBrowseService: parameter renamed accordingly.
- OpcUaBrowserDialog: collapse the duplicate ConnectionName parameters
  (display label and routing key are the same string).
- Task 10: DataConnectionManagerActor forwards BrowseOpcUaNodeCommand to
  its child by name (owns ConnectionNotFound); DataConnectionActor adds
  the receive across all three lifecycle states (Connecting / Connected
  / Reconnecting) and maps adapter outcomes to BrowseFailureKind
  (NotBrowsable / ConnectionNotConnected / Timeout / ServerError).
- Task 17: SetFailure in OpcUaBrowserDialog implements the full
  BrowseFailureKind switch with friendly UI messages.
- Tests: DataConnectionManagerBrowseHandlerTests covers ConnectionNotFound,
  NotBrowsable, success, and ConnectionNotConnectedException paths.

src/ZB.MOM.WW.ScadaBridge.DataConnectionLayer/Actors/DataConnectionManagerActor.cs

@@ -2,6 +2,7 @@ using Akka.Actor;
 using Akka.Event;
 using ZB.MOM.WW.ScadaBridge.Commons.Interfaces.Protocol;
 using ZB.MOM.WW.ScadaBridge.Commons.Messages.DataConnection;
+using ZB.MOM.WW.ScadaBridge.Commons.Messages.Management;
 using ZB.MOM.WW.ScadaBridge.HealthMonitoring;
 using ZB.MOM.WW.ScadaBridge.SiteEventLogging;
 
@@ -45,6 +46,7 @@ public class DataConnectionManagerActor : ReceiveActor
         Receive<WriteTagRequest>(HandleRouteWrite);
         Receive<RemoveConnectionCommand>(HandleRemoveConnection);
         Receive<GetAllHealthReports>(HandleGetAllHealthReports);
+        Receive<BrowseOpcUaNodeCommand>(HandleBrowse);
     }
 
     private void HandleCreateConnection(CreateConnectionCommand command)
@@ -111,6 +113,33 @@ public class DataConnectionManagerActor : ReceiveActor
         }
     }
 
+    /// <summary>
+    /// Routes a <see cref="BrowseOpcUaNodeCommand"/> from the central UI's OPC UA
+    /// Tag Browser to the child <see cref="DataConnectionActor"/> that owns the
+    /// named connection. The manager is the only actor that knows whether a
+    /// connection exists at this site — so it owns the
+    /// <see cref="BrowseFailureKind.ConnectionNotFound"/> failure. Everything
+    /// else (capability check, session state, server errors) lives inside the
+    /// child where the adapter is held.
+    /// </summary>
+    private void HandleBrowse(BrowseOpcUaNodeCommand command)
+    {
+        if (_connectionActors.TryGetValue(command.ConnectionName, out var actor))
+        {
+            actor.Forward(command);
+        }
+        else
+        {
+            _log.Warning("No connection actor for {0} during browse", command.ConnectionName);
+            Sender.Tell(new BrowseOpcUaNodeResult(
+                Array.Empty<BrowseNode>(),
+                Truncated: false,
+                new BrowseFailure(
+                    BrowseFailureKind.ConnectionNotFound,
+                    $"No data connection named '{command.ConnectionName}' at this site.")));
+        }
+    }
+
     private void HandleRemoveConnection(RemoveConnectionCommand command)
     {
         if (_connectionActors.TryGetValue(command.ConnectionName, out var actor))