Improve delete UX and prepaid credit time display.

Show minutes and local expiry for resource credits; add shared delete hook with row/card loading overlays, detail-page deleting modal, and disabled controls to prevent double-delete.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/src/components/delete-button-label.tsx

@@ -0,0 +1,14 @@
+'use client';
+
+import { Clock } from 'lucide-react';
+
+export function DeleteButtonLabel({ loading, label = 'Delete' }: { loading?: boolean; label?: string }) {
+  if (loading) {
+    return (
+      <>
+        <Clock className="w-3 h-3 inline animate-spin" /> Deleting…
+      </>
+    );
+  }
+  return <>{label}</>;
+}