fix(admin): eliminate GoTrue empty-body 500s under bulk load (retry-all + undici keep-alive + sequential bulk), CSV formula-injection guard

app/admin/page.tsx

@@ -1,6 +1,7 @@
 import Link from 'next/link';
 import { computeMetrics } from '@/lib/admin/metrics';
 import { getSupabaseAdmin } from '@/lib/supabase/admin';
+import { withAdminRetry } from '@/lib/admin/retry';
 import { formatBytes, formatDate } from '@/lib/format';
 
 export const dynamic = 'force-dynamic';
@@ -18,10 +19,12 @@ export default async function AdminOverviewPage() {
   const admin = getSupabaseAdmin();
 
   // Recent signups (latest 5 users).
-  const { data: recentUsersData } = await admin.auth.admin.listUsers({
-    page: 1,
-    perPage: 5,
-  });
+  const { data: recentUsersData } = await withAdminRetry(() =>
+    admin.auth.admin.listUsers({
+      page: 1,
+      perPage: 5,
+    }),
+  );
   const recentUsers = recentUsersData?.users ?? [];
 
   // Over-quota tunnels (compute in memory).