refactor(apps): 主题系统迁移至 ColorScheme + 扩展架构并支持 Dark Mode

apps/lib/features/auth/presentation/widgets/password_field.dart

@@ -1,7 +1,6 @@
 import 'package:flutter/material.dart';
 
 import '../../../../core/l10n/l10n.dart';
-import '../../../../core/theme/design_tokens.dart';
 import 'auth_field.dart';
 
 class PasswordField extends StatefulWidget {
@@ -33,6 +32,8 @@ class _PasswordFieldState extends State<PasswordField> {
 
   @override
   Widget build(BuildContext context) {
+    final colorScheme = Theme.of(context).colorScheme;
+
     return AuthField(
       label: widget.label,
       hint: widget.hint,
@@ -46,7 +47,7 @@ class _PasswordFieldState extends State<PasswordField> {
             : context.l10n.authHidePassword,
         icon: Icon(
           _obscured ? Icons.visibility_off_rounded : Icons.visibility_rounded,
-          color: AppColors.authInputIcon,
+          color: colorScheme.onSurfaceVariant,
         ),
       ),
     );