feat(theme): 重构颜色系统为双主题设计并添加渐变组件

- 引入 "The Kinetic Vault"（深色）和 "The Ethereal Terminal"（浅色）双主题系统
- 重构颜色方案，使用层次化 surface 容器替代边框，遵循无边框设计规则
- 添加渐变预设（CTA、买入/卖出、资产卡片）和渐变按钮组件
- 更新圆角系统，明确按钮、卡片、输入框和标签的圆角规范
- 统一文本样式系统，使用 Space Grotesk（标题）和 Manrope（正文）字体
- 更新现有组件（AssetCard、CoinCard、TradeButton）以遵循新设计规范
- 添加向后兼容的已废弃常量，确保现有代码正常运行

flutter_monisuo/lib/ui/components/asset_card.dart

@@ -1,8 +1,16 @@
 import 'package:flutter/material.dart';
 import 'package:shadcn_ui/shadcn_ui.dart';
+import 'package:flutter_animate/flutter_animate.dart';
 import '../../core/theme/app_color_scheme.dart';
+import '../../core/theme/app_spacing.dart';
 
 /// 资产卡片组件 - 用于显示资产总览
+///
+/// 设计规则 ("The Kinetic Vault"):
+/// - 渐变背景: Neon Blue → Electric Purple
+/// - 圆角: xl (16px)
+/// - 无边框，使用渐变层次
+/// - 微妙阴影: 10% black, blur 10px
 class AssetCard extends StatelessWidget {
   final String title;
   final String balance;
@@ -13,16 +21,16 @@ class AssetCard extends StatelessWidget {
   final Gradient? gradient;
   final VoidCallback? onTap;
 
-  // 默认渐变色 - 使用品牌青绿色
+  /// 默认渐变色 - Neon Blue → Electric Purple
   static const defaultGradient = LinearGradient(
-    colors: [AppColorScheme.primaryDark, Color(0xFF00B894)],
+    colors: [AppColorScheme.darkPrimary, AppColorScheme.darkSecondary],
     begin: Alignment.topLeft,
     end: Alignment.bottomRight,
   );
 
-  // 深色渐变
-  static const darkGradient = LinearGradient(
-    colors: [Color(0xFF1E3A5F), Color(0xFF0D253F)],
+  /// 翡翠渐变 - 用于盈利展示
+  static const emeraldGradient = LinearGradient(
+    colors: [AppColorScheme.darkTertiary, Color(0xFF7de8b8)],
     begin: Alignment.topLeft,
     end: Alignment.bottomRight,
   );
@@ -48,10 +56,10 @@ class AssetCard extends StatelessWidget {
       onTap: onTap,
       child: Container(
         width: double.infinity,
-        padding: const EdgeInsets.all(24),
+        padding: const EdgeInsets.all(AppSpacing.lg),
         decoration: BoxDecoration(
           gradient: cardGradient,
-          borderRadius: BorderRadius.circular(20),
+          borderRadius: BorderRadius.circular(AppRadius.xl),
           boxShadow: [
             BoxShadow(
               color: Colors.black.withValues(alpha: 0.1),
@@ -79,18 +87,19 @@ class AssetCard extends StatelessWidget {
                   ),
               ],
             ),
-            const SizedBox(height: 8),
-            // 余额
+            const SizedBox(height: AppSpacing.sm),
+            // 余额 - 大标题
             Text(
               balance,
               style: theme.textTheme.h1.copyWith(
                 fontWeight: FontWeight.bold,
                 color: Colors.white,
+                fontSize: 32,
               ),
             ),
             // 盈亏信息
             if (profit != null) ...[
-              const SizedBox(height: 12),
+              const SizedBox(height: AppSpacing.md),
               Row(
                 children: [
                   Icon(
@@ -108,7 +117,7 @@ class AssetCard extends StatelessWidget {
             ],
             // 子项
             if (items != null && items!.isNotEmpty) ...[
-              const SizedBox(height: 20),
+              const SizedBox(height: AppSpacing.lg),
               Row(
                 mainAxisAlignment: MainAxisAlignment.spaceBetween,
                 children: items!.map((item) => _buildItem(item)).toList(),
@@ -154,6 +163,11 @@ class AssetItem {
 }
 
 /// 简洁资产卡片 - 用于列表中显示
+///
+/// 设计规则:
+/// - 使用 surface 层次而非边框
+/// - 圆角: xl (16px)
+/// - 涨跌标签: 15% 透明度背景
 class AssetCardCompact extends StatelessWidget {
   final String title;
   final String balance;
@@ -176,7 +190,7 @@ class AssetCardCompact extends StatelessWidget {
     final isValueUp = isUp ?? true;
 
     return ShadCard(
-      padding: const EdgeInsets.all(16),
+      padding: const EdgeInsets.all(AppSpacing.md),
       child: InkWell(
         onTap: onTap,
         child: Row(
@@ -204,7 +218,7 @@ class AssetCardCompact extends StatelessWidget {
                 padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 6),
                 decoration: BoxDecoration(
                   color: getChangeBackgroundColor(isValueUp),
-                  borderRadius: BorderRadius.circular(6),
+                  borderRadius: BorderRadius.circular(AppRadius.sm),
                 ),
                 child: Text(
                   change!,