fix(auth): 登录异常改为居中吐司

lib/pages/auth/auth_view.dart

@@ -12,7 +12,7 @@ import '../../core/platform/keyboard_inset.dart';
 import '../../core/theme/app_colors.dart';
 import '../../core/theme/app_dimens.dart';
 import '../../core/theme/app_theme.dart';
-import '../../core/widgets/centered_error_dialog.dart';
+import '../../core/widgets/centered_toast.dart';
 import '../../core/widgets/subpage_header.dart';
 import '../../l10n/app_localizations.dart';
 import 'auth_logic.dart';
@@ -251,11 +251,7 @@ class _AuthPageState extends State<AuthPage> {
       if (mounted) setState(() => _logic.busy = false);
     }
     if (!mounted || failureMessage == null) return;
-    await showCenteredErrorDialog(
-      context,
-      title: _logic.signUpMode ? l10n.authRegisterFailed : l10n.authLoginFailed,
-      message: failureMessage,
-    );
+    showCenteredToast(context, failureMessage);
   }
 
   @override

lib/pages/auth/phone_auth_sheet.dart

@@ -11,7 +11,7 @@ import '../../core/data/services/auth_controller.dart';
 import '../../core/platform/haptics.dart';
 import '../../core/platform/keyboard_inset.dart';
 import '../../core/theme/app_colors.dart';
-import '../../core/widgets/centered_error_dialog.dart';
+import '../../core/widgets/centered_toast.dart';
 import '../../l10n/app_localizations.dart';
 
 const double _fieldHeight = 52;
@@ -187,7 +187,7 @@ class _PhoneAuthSheetState extends State<PhoneAuthSheet> {
       if (mounted) setState(() => _sending = false);
     }
     if (mounted && failureMessage != null) {
-      await _showFailure(failureMessage);
+      showCenteredToast(context, failureMessage);
     }
   }
 
@@ -235,19 +235,10 @@ class _PhoneAuthSheetState extends State<PhoneAuthSheet> {
       if (mounted) setState(() => _submitting = false);
     }
     if (mounted && failureMessage != null) {
-      await _showFailure(failureMessage);
+      showCenteredToast(context, failureMessage);
     }
   }
 
-  Future<void> _showFailure(String message) {
-    final l10n = AppLocalizations.of(context)!;
-    return showCenteredErrorDialog(
-      context,
-      title: _signUp ? l10n.authRegisterFailed : l10n.authLoginFailed,
-      message: message,
-    );
-  }
-
   void _switchMode() {
     setState(() {
       _signUp = !_signUp;