feat: Implement admin dashboard with user management, statistics, and role-based access control.

types/next-auth.d.ts

@@ -0,0 +1,20 @@
+import NextAuth, { type DefaultSession } from 'next-auth';
+
+declare module 'next-auth' {
+    interface Session {
+        user: {
+            id: string;
+            isAdmin: boolean;
+        } & DefaultSession['user'];
+    }
+
+    interface User {
+        isAdmin?: boolean;
+    }
+}
+
+declare module 'next-auth/jwt' {
+    interface JWT {
+        isAdmin?: boolean;
+    }
+}