userfront 로그인 후 /dashboard로 이동하게 변경

userfront/lib/features/auth/presentation/signup_screen.dart

@@ -3,6 +3,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:go_router/go_router.dart';
 import 'package:userfront/i18n.dart';
+import '../../../core/i18n/locale_utils.dart';
 import '../../../core/services/auth_proxy_service.dart';
 
 class SignupScreen extends StatefulWidget {
@@ -345,7 +346,7 @@ class _SignupScreenState extends State<SignupScreen> {
         content: Text(tr('msg.userfront.signup.success.body')),
         actions: [
           TextButton(
-            onPressed: () => context.go('/signin'),
+            onPressed: () => context.go(buildLocalizedSigninPath(Uri.base)),
             child: Text(tr('ui.userfront.signup.success.action')),
           ),
         ],