fix: correct user authentication check in messages page

The /api/auth/me endpoint returns { authenticated: true, id, username, ... }
not { user: {...} }. Fixed the messages page to correctly parse the response.

src/app/messages/page.tsx

@@ -53,7 +53,17 @@ export default function MessagesPage() {
       const res = await fetch('/api/auth/me');
       if (res.ok) {
         const data = await res.json();
-        setUser(data.user);
+        if (data.authenticated) {
+          setUser({
+            id: data.id,
+            username: data.username,
+            first_name: data.first_name,
+            last_name: data.last_name,
+            role: data.role,
+          });
+        } else {
+          window.location.href = '/login';
+        }
       } else {
         window.location.href = '/login';
       }