fix(ui): templates root-menu Escape + double-menu guard + reorder disabled tests (#258)

- Root context menu now has tabindex/focus + Escape-key close (OnRootMenuKeyDown) mirroring the node menu
- Opening root menu calls _tree.DismissNodeContextMenu(); opening node menu fires OnNodeContextMenuOpened → DismissRootContextMenu so only one menu is ever visible
- Add FolderContextMenu_MoveUp_IsDisabled_OnFirstSibling and FolderContextMenu_MoveDown_IsDisabled_OnLastSibling bUnit tests

src/ZB.MOM.WW.ScadaBridge.CentralUI/Components/Shared/TemplateFolderTree.razor

@@ -21,7 +21,8 @@
           SelectedKeys="SelectedKeys"
           SelectedKeysChanged="SelectedKeysChanged"
           InitiallyExpanded="@(_initiallyExpanded)"
-          StorageKey="@StorageKey">
+          StorageKey="@StorageKey"
+          OnNodeContextMenuOpened="OnNodeContextMenuOpened">
     <NodeContent Context="node">
         @if (NodeContent != null)
         {
@@ -72,6 +73,8 @@
     [Parameter] public RenderFragment? EmptyContent { get; set; }
     [Parameter] public EventCallback<TemplateTreeNode> OnNodeClick { get; set; }
     [Parameter] public string? StorageKey { get; set; }
+    /// <summary>Raised when a node context menu opens; forwarded from the inner TreeView.</summary>
+    [Parameter] public EventCallback OnNodeContextMenuOpened { get; set; }
 
     /// <summary>
     /// Optional: caller-supplied extra leaves to nest under a template. Used by
@@ -225,4 +228,10 @@
 
     /// <summary>Forwarded to the inner TreeView so callers can drive expand/collapse.</summary>
     public void CollapseAll() => _tree?.CollapseAll();
+
+    /// <summary>
+    /// Close any open node context menu. Called by the host page when it opens the
+    /// root context menu so both menus are never visible simultaneously.
+    /// </summary>
+    public void DismissNodeContextMenu() => _tree?.DismissContextMenu();
 }