refactor(theme): 迁移主题感知颜色至 ThemeExtension

- 创建 AppThemeColors ThemeExtension 类，统一管理主题感知颜色（涨跌色、卡片背景、渐变等）
- 从 AppColorScheme 移除主题感知辅助函数，仅保留静态颜色常量
- 在 AppTheme 中注册 ThemeExtension，支持深色/浅色主题工厂
- 重构所有 UI 组件使用 context.appColors 访问主题颜色，替代硬编码的 AppColorScheme 方法调用
- 移除组件中重复的 isDark 判断逻辑，简化颜色获取方式
- 保持向后兼容性，所有现有功能不变

flutter_monisuo/lib/ui/pages/trade/components/confirm_dialog.dart

@@ -1,7 +1,7 @@
 import 'package:flutter/material.dart';
-import '../../../../core/theme/app_color_scheme.dart';
 import '../../../../core/theme/app_spacing.dart';
 import '../../../../core/theme/app_theme.dart';
+import '../../../../core/theme/app_theme_extension.dart';
 import '../../../components/glass_panel.dart';
 import '../../../components/neon_glow.dart';
 
@@ -27,11 +27,9 @@ class ConfirmDialog extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final colorScheme = Theme.of(context).colorScheme;
-    final isDark = Theme.of(context).brightness == Brightness.dark;
     final actionColor = isBuy
-        ? AppColorScheme.getUpColor(isDark)
-        : AppColorScheme.getDownColor(isDark);
+        ? context.appColors.up
+        : context.appColors.down;
 
     return Dialog(
       backgroundColor: const Color(0x00000000),
@@ -49,14 +47,14 @@ class ConfirmDialog extends StatelessWidget {
               ),
             ),
             SizedBox(height: AppSpacing.lg),
-            _dialogRow(context, '交易对', '$coinCode/USDT', colorScheme),
+            _dialogRow(context, '交易对', '$coinCode/USDT'),
             SizedBox(height: AppSpacing.sm),
-            _dialogRow(context, '委托价格', '$price USDT', colorScheme),
+            _dialogRow(context, '委托价格', '$price USDT'),
             SizedBox(height: AppSpacing.sm),
-            _dialogRow(context, '交易金额', '$amount USDT', colorScheme,
+            _dialogRow(context, '交易金额', '$amount USDT',
                 valueColor: actionColor),
             SizedBox(height: AppSpacing.sm),
-            _dialogRow(context, '交易数量', '$quantity $coinCode', colorScheme),
+            _dialogRow(context, '交易数量', '$quantity $coinCode'),
             SizedBox(height: AppSpacing.lg),
             Row(
               children: [
@@ -87,7 +85,7 @@ class ConfirmDialog extends StatelessWidget {
     );
   }
 
-  Widget _dialogRow(BuildContext context, String label, String value, ColorScheme colorScheme,
+  Widget _dialogRow(BuildContext context, String label, String value,
       {Color? valueColor}) {
     return Row(
       mainAxisAlignment: MainAxisAlignment.spaceBetween,
@@ -95,11 +93,11 @@ class ConfirmDialog extends StatelessWidget {
         Text(label,
             style: AppTextStyles.headlineMedium(context).copyWith(
               fontWeight: FontWeight.w400,
-              color: colorScheme.onSurfaceVariant,
+              color: context.colors.onSurfaceVariant,
             )),
         Text(value,
             style: AppTextStyles.numberMedium(context).copyWith(
-              color: valueColor ?? colorScheme.onSurface,
+              color: valueColor ?? context.colors.onSurface,
             )),
       ],
     );