feat: some changes and admin

nextjs/src/app/admin/no-access/page.tsx

@@ -0,0 +1,18 @@
+import Link from 'next/link';
+
+import style from '@/styles/admin.module.scss';
+
+export default function AdminNoAccessPage() {
+  return (
+    <div className={style.card}>
+      <h1 className={style.title}>No admin access</h1>
+      <p className={style.sub}>
+        Your account is approved, but you do not have administrator privileges for content management. Ask an existing admin to
+        grant you the admin role.
+      </p>
+      <p>
+        <Link href="/admin">Dashboard</Link>
+      </p>
+    </div>
+  );
+}