fix: add missing closing div in DashboardPage.tsx navigation

frontend/src/pages/DashboardPage.tsx

@@ -375,6 +375,7 @@ export default function DashboardPage() {
                                     </Link>
                                 )}
                             </div>
+                        </div>
 
                         {/* Center: Date/Time */}
                         <div className="hidden lg:flex flex-col items-center justify-center">