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.CentralUI/Components/Dialogs/OpcUaBrowserDialog.razor

@@ -57,7 +57,12 @@
 
 @code {
     [Parameter] public string SiteId { get; set; } = "";
-    [Parameter] public int DataConnectionId { get; set; }
+    /// <summary>
+    /// Name of the site-local data connection. Serves both as the modal-header
+    /// display label AND as the routing key for the browse round-trip — the
+    /// site's <c>DataConnectionManagerActor</c> indexes its children by
+    /// connection name (no id-keyed lookup at the site).
+    /// </summary>
     [Parameter] public string ConnectionName { get; set; } = "";
     [Parameter] public string? InitialNodeId { get; set; }
     [Parameter] public EventCallback<string> OnSelected { get; set; }
@@ -105,7 +110,7 @@
         _rootNodes = new();
         StateHasChanged();
 
-        var result = await BrowseService.BrowseChildrenAsync(SiteId, DataConnectionId, parentNodeId: null);
+        var result = await BrowseService.BrowseChildrenAsync(SiteId, ConnectionName, parentNodeId: null);
         if (result.Failure is not null)
         {
             SetFailure(result.Failure);
@@ -130,7 +135,7 @@
         {
             node.Loading = true;
             StateHasChanged();
-            var result = await BrowseService.BrowseChildrenAsync(SiteId, DataConnectionId, node.NodeId);
+            var result = await BrowseService.BrowseChildrenAsync(SiteId, ConnectionName, node.NodeId);
             node.Loading = false;
 
             if (result.Failure is not null)
@@ -155,12 +160,23 @@
         _manualNodeId = node.NodeId;
     }
 
-    // NOTE: Task 17 will replace this body with the full BrowseFailureKind switch
-    //       that maps each failure kind to a friendly UI message.
+    // Task 17: map each BrowseFailureKind to a friendly UI message. The raw
+    // failure.Message is surfaced verbatim only for ServerError (which carries
+    // the OPC UA SDK's own Bad_* text) and as the default fallback for any
+    // future failure kind added without a UI mapping.
     private void SetFailure(BrowseFailure failure)
     {
         _failure = failure;
-        _failureMessage = failure.Message;
+        _failureMessage = failure.Kind switch
+        {
+            BrowseFailureKind.ConnectionNotFound      => "Connection no longer exists at the site.",
+            BrowseFailureKind.ConnectionNotConnected  => "OPC UA session not connected — retry shortly or use manual entry.",
+            BrowseFailureKind.NotBrowsable            => "This connection does not support browsing.",
+            BrowseFailureKind.Timeout                 => "Browse timed out — the server may be slow. Try again or enter the node id manually.",
+            BrowseFailureKind.ServerError             => $"OPC UA server error: {failure.Message}",
+            _                                          => failure.Message
+        };
+        StateHasChanged();
     }
 
     private Task RetryRootLoad() => LoadRootAsync();

src/ZB.MOM.WW.ScadaBridge.CentralUI/Services/IOpcUaBrowseService.cs

@@ -21,17 +21,17 @@ public interface IOpcUaBrowseService
 {
     /// <summary>
     /// Enumerates the immediate children of an OPC UA node on the live server
-    /// backing <paramref name="dataConnectionId"/> at <paramref name="siteId"/>.
+    /// backing <paramref name="connectionName"/> at <paramref name="siteId"/>.
     /// Pass <c>null</c> for <paramref name="parentNodeId"/> to browse from the
     /// server root (ObjectsFolder).
     /// </summary>
     /// <param name="siteId">The target site identifier.</param>
-    /// <param name="dataConnectionId">Id of the site-local data connection to browse against.</param>
+    /// <param name="connectionName">Name of the site-local data connection to browse against — the site's <c>DataConnectionManagerActor</c> indexes its children by name.</param>
     /// <param name="parentNodeId">Node to browse, or <c>null</c> to browse from the server root.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
     Task<BrowseOpcUaNodeResult> BrowseChildrenAsync(
         string siteId,
-        int dataConnectionId,
+        string connectionName,
         string? parentNodeId,
         CancellationToken cancellationToken = default);
 }

src/ZB.MOM.WW.ScadaBridge.CentralUI/Services/OpcUaBrowseService.cs

@@ -37,7 +37,7 @@ public sealed class OpcUaBrowseService : IOpcUaBrowseService
     /// <inheritdoc/>
     public async Task<BrowseOpcUaNodeResult> BrowseChildrenAsync(
         string siteId,
-        int dataConnectionId,
+        string connectionName,
         string? parentNodeId,
         CancellationToken cancellationToken = default)
     {
@@ -56,7 +56,7 @@ public sealed class OpcUaBrowseService : IOpcUaBrowseService
         {
             return await _communication.BrowseOpcUaNodeAsync(
                 siteId,
-                new BrowseOpcUaNodeCommand(dataConnectionId, parentNodeId),
+                new BrowseOpcUaNodeCommand(connectionName, parentNodeId),
                 cancellationToken);
         }
         catch (TimeoutException ex)