修复flutter analyze提示，更新版本至v1.0.0-Beta4.8

frontend/lib/pages/login_page.dart

@@ -12,7 +12,7 @@ class LoginPage extends StatefulWidget {
   const LoginPage({super.key});
 
   @override
-  _LoginPageState createState() => _LoginPageState();
+  State<LoginPage> createState() => _LoginPageState();
 }
 
 class _LoginPageState extends State<LoginPage> {
@@ -64,9 +64,9 @@ class _LoginPageState extends State<LoginPage> {
       if (!mounted) {
         return;
       }
-      ScaffoldMessenger.of(context).showSnackBar(
-        SnackBar(content: Text(l10n.networkError)),
-      );
+      ScaffoldMessenger.of(
+        context,
+      ).showSnackBar(SnackBar(content: Text(l10n.networkError)));
     } finally {
       if (mounted) setState(() => _isLoading = false);
     }
@@ -177,7 +177,7 @@ class _LoginPageState extends State<LoginPage> {
                 TextButton(
                   onPressed: () => Navigator.push(
                     context,
-                    MaterialPageRoute(builder: (_) => RegisterPage()),
+                    MaterialPageRoute(builder: (_) => const RegisterPage()),
                   ),
                   child: Text(l10n.dontHaveAccount),
                 ),