Add auth redirect to site admin page

apps/next/src/app/(payload)/admin/layout.tsx

@@ -0,0 +1,27 @@
+import type { Metadata } from 'next';
+import { redirect } from 'next/navigation';
+import { isAuthenticatedNextjs } from '@convex-dev/auth/nextjs/server';
+
+export const generateMetadata = (): Metadata => {
+  return {
+    title: 'Site Admin',
+    robots: {
+      index: false,
+      follow: false,
+      googleBot: {
+        index: false,
+        follow: false,
+      },
+    },
+  };
+};
+
+const AdminLayout = async ({
+  children,
+}: Readonly<{ children: React.ReactNode }>) => {
+  if (!(await isAuthenticatedNextjs())) {
+    redirect('/sign-in');
+  }
+  return <>{children}</>;
+};
+export default AdminLayout;