fix(ui): use canonical close icon in admin panel

packages/ui-react/src/AdminNavigationPanel.tsx

@@ -1,6 +1,7 @@
 import type { HTMLAttributes, ReactNode } from "react";
 import { cn } from "./cn.js";
 import { SortableList } from "./DragDrop.js";
+import { Icon } from "./Icon.js";
 
 export interface AdminNavigationContext {
   id: string;
@@ -63,7 +64,7 @@ export function AdminNavigationPanel({
         <div className="nodedc-admin-panel__head-actions">
           {headerActions}
           <button type="button" className="nodedc-admin-panel__close" aria-label={closeLabel} onClick={onClose}>
-            <span className="nodedc-close-mark" aria-hidden="true" />
+            <Icon name="close" size={16} strokeWidth={1.6} />
           </button>
         </div>
       </header>