Add admin restart flow and loading indicators

src/ui/IconButton.tsx

@@ -1,4 +1,5 @@
 import type { ButtonHTMLAttributes, ReactNode } from 'react';
+import { BusyRing } from './BusyRing';
 
 export type IconButtonVariant = 'neutral' | 'add' | 'danger';
 
@@ -36,8 +37,10 @@ export function IconButton({
       aria-label={label}
       data-tooltip={tooltipText}
       disabled={disabled || loading}
+      aria-busy={loading || undefined}
     >
-      {loading ? <span className="ui-button-spinner" aria-hidden="true" /> : icon}
+      {loading ? <BusyRing /> : null}
+      {icon}
     </button>
   );
 }