feat(auth): 登录异常改为居中弹窗

lib/pages/auth/auth_view.dart

@@ -12,6 +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/subpage_header.dart';
 import '../../l10n/app_localizations.dart';
 import 'auth_logic.dart';
@@ -227,6 +228,7 @@ class _AuthPageState extends State<AuthPage> {
       _logic.errorMessage = null;
     });
     final auth = context.read<AuthController>();
+    String? failureMessage;
     try {
       if (_logic.signUpMode) {
         await auth.register(
@@ -242,14 +244,18 @@ class _AuthPageState extends State<AuthPage> {
       if (!mounted) return;
       Navigator.of(context).maybePop();
     } on ApiException catch (error) {
-      if (!mounted) return;
-      setState(() => _logic.errorMessage = error.message);
+      failureMessage = error.message;
     } catch (_) {
-      if (!mounted) return;
-      setState(() => _logic.errorMessage = l10n.authNetworkError);
+      failureMessage = l10n.authNetworkError;
     } finally {
       if (mounted) setState(() => _logic.busy = false);
     }
+    if (!mounted || failureMessage == null) return;
+    await showCenteredErrorDialog(
+      context,
+      title: _logic.signUpMode ? l10n.authRegisterFailed : l10n.authLoginFailed,
+      message: failureMessage,
+    );
   }
 
   @override

lib/pages/auth/phone_auth_sheet.dart

@@ -11,6 +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 '../../l10n/app_localizations.dart';
 
 const double _fieldHeight = 52;
@@ -164,6 +165,7 @@ class _PhoneAuthSheetState extends State<PhoneAuthSheet> {
     });
     final haptics = context.read<Haptics>();
     final auth = context.read<AuthController>();
+    String? failureMessage;
     await haptics.lightImpact();
     try {
       await auth.sendOtp(
@@ -173,16 +175,20 @@ class _PhoneAuthSheetState extends State<PhoneAuthSheet> {
       if (!mounted) return;
       _startCountdown();
       setState(() => _error = null);
-      ScaffoldMessenger.of(context)
-          .showSnackBar(SnackBar(content: Text(l10n.authCodeSent)));
+      ScaffoldMessenger.of(
+        context,
+      ).showSnackBar(SnackBar(content: Text(l10n.authCodeSent)));
       _codeFocus.requestFocus();
     } on ApiException catch (error) {
-      if (mounted) setState(() => _error = error.message);
+      failureMessage = error.message;
     } catch (_) {
-      if (mounted) setState(() => _error = l10n.authNetworkError);
+      failureMessage = l10n.authNetworkError;
     } finally {
       if (mounted) setState(() => _sending = false);
     }
+    if (mounted && failureMessage != null) {
+      await _showFailure(failureMessage);
+    }
   }
 
   void _startCountdown() {
@@ -212,6 +218,7 @@ class _PhoneAuthSheetState extends State<PhoneAuthSheet> {
     });
     final haptics = context.read<Haptics>();
     final auth = context.read<AuthController>();
+    String? failureMessage;
     await haptics.lightImpact();
     try {
       if (_signUp) {
@@ -221,12 +228,24 @@ class _PhoneAuthSheetState extends State<PhoneAuthSheet> {
       }
       if (mounted) Navigator.of(context).pop(true);
     } on ApiException catch (error) {
-      if (mounted) setState(() => _error = error.message);
+      failureMessage = error.message;
     } catch (_) {
-      if (mounted) setState(() => _error = l10n.authNetworkError);
+      failureMessage = l10n.authNetworkError;
     } finally {
       if (mounted) setState(() => _submitting = false);
     }
+    if (mounted && failureMessage != null) {
+      await _showFailure(failureMessage);
+    }
+  }
+
+  Future<void> _showFailure(String message) {
+    final l10n = AppLocalizations.of(context)!;
+    return showCenteredErrorDialog(
+      context,
+      title: _signUp ? l10n.authRegisterFailed : l10n.authLoginFailed,
+      message: message,
+    );
   }
 
   void _switchMode() {