feat: add the admin page

apps/web/src/app/(dashboard)/admin/layout.tsx

@@ -0,0 +1,23 @@
+import { redirect } from 'next/navigation';
+
+import { isAdmin } from '@documenso/lib/';
+import { getRequiredServerComponentSession } from '@documenso/lib/next-auth/get-server-session';
+
+export type AdminLayoutProps = {
+  children: React.ReactNode;
+};
+
+export default async function AdminLayout({ children }: AdminLayoutProps) {
+  const user = await getRequiredServerComponentSession();
+  const isUserAdmin = isAdmin(user);
+
+  if (!user) {
+    redirect('/signin');
+  }
+
+  if (!isUserAdmin) {
+    redirect('/dashboard');
+  }
+
+  return <main className="mt-8 pb-8 md:mt-12 md:pb-12">{children}</main>;
+}