fix(centralui): pass siteId+connectionName into ShowAsync explicitly

Razor parameter binding propagates on the next render, so reading SiteId
inside LoadRootAsync raced against the parent's "set field, then call
ShowAsync()" pattern — central received an empty siteId and rejected
with "No ClusterClient for site ,". Take the values as args instead.

src/ZB.MOM.WW.ScadaBridge.CentralUI/Components/Dialogs/OpcUaBrowserDialog.razor

@@ -96,11 +96,18 @@
         public bool Truncated { get; set; }
     }
 
-    public async Task ShowAsync()
+    private string _runtimeSiteId = "";
+    private string _runtimeConnectionName = "";
+
+    public async Task ShowAsync(string siteId, string connectionName, string? initialNodeId)
     {
+        // Snapshot at click time. Razor parameter binding propagates on the next
+        // render, which would race the immediate LoadRootAsync below.
+        _runtimeSiteId = siteId;
+        _runtimeConnectionName = connectionName;
         _isVisible = true;
-        _manualNodeId = InitialNodeId ?? "";
-        _selectedNodeId = InitialNodeId;
+        _manualNodeId = initialNodeId ?? "";
+        _selectedNodeId = initialNodeId;
         await LoadRootAsync();
     }
 
@@ -110,7 +117,7 @@
         _rootNodes = new();
         StateHasChanged();
 
-        var result = await BrowseService.BrowseChildrenAsync(SiteId, ConnectionName, parentNodeId: null);
+        var result = await BrowseService.BrowseChildrenAsync(_runtimeSiteId, _runtimeConnectionName, parentNodeId: null);
         if (result.Failure is not null)
         {
             SetFailure(result.Failure);
@@ -135,7 +142,7 @@
         {
             node.Loading = true;
             StateHasChanged();
-            var result = await BrowseService.BrowseChildrenAsync(SiteId, ConnectionName, node.NodeId);
+            var result = await BrowseService.BrowseChildrenAsync(_runtimeSiteId, _runtimeConnectionName, node.NodeId);
             node.Loading = false;
 
             if (result.Failure is not null)

src/ZB.MOM.WW.ScadaBridge.CentralUI/Components/Pages/Deployment/InstanceConfigure.razor

@@ -573,7 +573,7 @@
                           ?? GetTemplateDefault(attrName);
 
         if (_browserRef is not null)
-            await _browserRef.ShowAsync();
+            await _browserRef.ShowAsync(_siteIdentifier, conn.Name, _browserInitial);
     }
 
     private void OnBrowserSelected(string nodeId)