refactor: 批量替换 shadcn_ui 为 Material Design 组件

## 样式主题重点优化

### 颜色映射（注重主题一致性）
- mutedForeground → onSurfaceVariant
- border → outline
- card → surfaceContainer
- destructive → error
- 保留所有 AppColorScheme 自定义颜色

### 文本样式映射
- theme.textTheme.h1/muted/large → AppTextStyles.xxx(context)
- 统一使用项目定义的文本样式系统

### 组件替换（20个文件）
- ShadApp → MaterialApp（移除 ShadThemeData）
- ShadButton → ElevatedButton/OutlinedButton
- ShadDialog → AlertDialog
- ShadInputFormField → MaterialInput
- ShadSelect → DropdownButtonFormField
- ShadCard → Card
- showShadDialog → showDialog

### 依赖变更
- 移除：shadcn_ui: ^0.52.1
- 添加：lucide_icons_flutter: ^2.0.0

### 业务逻辑保护
✅ 所有 onPressed/onChanged/validator 回调保持不变
✅ 所有 controller/focusNode 数据绑定保持不变
✅ 所有布局结构（Column/Row/Padding）保持不变
✅ 仅替换 UI 组件层，业务逻辑完全保留

flutter_monisuo/lib/ui/pages/home/header_bar.dart

@@ -1,6 +1,6 @@
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
-import 'package:shadcn_ui/shadcn_ui.dart';
+import 'package:lucide_icons_flutter/lucide_icons.dart';
 import '../../../core/theme/app_theme.dart';
 import '../../../core/theme/app_color_scheme.dart';
 import '../../../core/theme/app_spacing.dart';

flutter_monisuo/lib/ui/pages/home/home_page.dart

@@ -1,7 +1,7 @@
 import 'dart:async';
 import 'package:flutter/material.dart';
 import 'package:provider/provider.dart';
-import 'package:shadcn_ui/shadcn_ui.dart';
+import 'package:lucide_icons_flutter/lucide_icons.dart';
 import '../../../core/theme/app_theme.dart';
 import '../../../core/theme/app_spacing.dart';
 import '../../../core/theme/app_theme_extension.dart';
@@ -87,12 +87,12 @@ class _HomePageState extends State<HomePage>
     super.build(context);
 
     return Scaffold(
-      backgroundColor: context.colors.background,
+      backgroundColor: Theme.of(context).colorScheme.background,
       body: Consumer<AssetProvider>(
         builder: (context, provider, _) {
           return RefreshIndicator(
             onRefresh: () => provider.refreshAll(force: true),
-            color: context.colors.primary,
+            color: Theme.of(context).colorScheme.primary,
             child: SingleChildScrollView(
               physics: const AlwaysScrollableScrollPhysics(),
               padding: EdgeInsets.only(
@@ -270,7 +270,7 @@ class _AssetCardState extends State<_AssetCard> {
                 child: Container(
                   padding: EdgeInsets.symmetric(horizontal: 10, vertical: 5),
                   decoration: BoxDecoration(
-                    color: context.colors.primary,
+                    color: Theme.of(context).colorScheme.primary,
                     borderRadius: BorderRadius.circular(AppRadius.sm),
                   ),
                   child: Row(
@@ -280,7 +280,7 @@ class _AssetCardState extends State<_AssetCard> {
                       Text(
                         '充值',
                         style: AppTextStyles.labelLarge(context).copyWith(
-                          color: context.colors.onPrimary,
+                          color: Theme.of(context).colorScheme.onPrimary,
                           fontSize: 12,
                         ),
                       ),
@@ -359,9 +359,9 @@ class _WelfareCard extends StatelessWidget {
         width: double.infinity,
         padding: EdgeInsets.all(AppSpacing.lg),
         decoration: BoxDecoration(
-          color: context.colors.surface,
+          color: Theme.of(context).colorScheme.surface,
           borderRadius: BorderRadius.circular(AppRadius.xl),
-          border: Border.all(color: context.colors.outlineVariant.withValues(alpha: 0.2)),
+          border: Border.all(color: Theme.of(context).colorScheme.outlineVariant.withValues(alpha: 0.2)),
         ),
         child: Row(
           children: [
@@ -370,12 +370,12 @@ class _WelfareCard extends StatelessWidget {
               width: 48,
               height: 48,
               decoration: BoxDecoration(
-                color: context.colors.primary.withValues(alpha: 0.15),
+                color: Theme.of(context).colorScheme.primary.withValues(alpha: 0.15),
                 borderRadius: BorderRadius.circular(AppRadius.lg),
               ),
               child: Icon(
                 LucideIcons.gift,
-                color: context.colors.primary,
+                color: Theme.of(context).colorScheme.primary,
                 size: 24,
               ),
             ),
@@ -426,7 +426,7 @@ class _WelfareCard extends StatelessWidget {
                         style: AppTextStyles.bodySmall(context).copyWith(
                           fontSize: 10,
                           fontWeight: FontWeight.bold,
-                          color: context.colors.onPrimary,
+                          color: Theme.of(context).colorScheme.onPrimary,
                         ),
                       ),
                     ),
@@ -504,13 +504,13 @@ class _EmptyHoldings extends StatelessWidget {
       width: double.infinity,
       padding: EdgeInsets.symmetric(vertical: AppSpacing.xxl, horizontal: AppSpacing.lg),
       decoration: BoxDecoration(
-        color: context.colors.surfaceContainerLow.withValues(alpha: 0.5),
+        color: Theme.of(context).colorScheme.surfaceContainerLow.withValues(alpha: 0.5),
         borderRadius: BorderRadius.circular(AppRadius.xxl),
-        border: Border.all(color: context.colors.outlineVariant.withValues(alpha: 0.1)),
+        border: Border.all(color: Theme.of(context).colorScheme.outlineVariant.withValues(alpha: 0.1)),
       ),
       child: Column(
         children: [
-          Icon(LucideIcons.wallet, size: 48, color: context.colors.onSurfaceVariant),
+          Icon(LucideIcons.wallet, size: 48, color: Theme.of(context).colorScheme.onSurfaceVariant),
           SizedBox(height: AppSpacing.md),
           Text(
             '暫無持倉',
@@ -542,9 +542,9 @@ class _HoldingsList extends StatelessWidget {
 
     return Container(
       decoration: BoxDecoration(
-        color: context.colors.surface.withValues(alpha: 0.5),
+        color: Theme.of(context).colorScheme.surface.withValues(alpha: 0.5),
         borderRadius: BorderRadius.circular(AppRadius.xxl),
-        border: Border.all(color: context.colors.outlineVariant.withValues(alpha: 0.1)),
+        border: Border.all(color: Theme.of(context).colorScheme.outlineVariant.withValues(alpha: 0.1)),
       ),
       child: ListView.separated(
         shrinkWrap: true,

flutter_monisuo/lib/ui/pages/home/hot_coins_section.dart

@@ -1,5 +1,4 @@
 import 'package:flutter/material.dart';
-import 'package:shadcn_ui/shadcn_ui.dart';
 import '../../../core/theme/app_theme.dart';
 import '../../../core/theme/app_spacing.dart';
 import '../../../core/theme/app_theme_extension.dart';
@@ -36,9 +35,9 @@ class HotCoinsSection extends StatelessWidget {
         // Card
         Container(
           decoration: BoxDecoration(
-            color: context.colors.surfaceContainer,
+            color: Theme.of(context).colorScheme.surfaceContainer,
             border: Border.all(
-              color: context.colors.outlineVariant,
+              color: Theme.of(context).colorScheme.outlineVariant,
               width: 1,
             ),
             borderRadius: BorderRadius.circular(AppRadius.xl),

flutter_monisuo/lib/ui/pages/home/quick_actions_row.dart

@@ -1,5 +1,5 @@
 import 'package:flutter/material.dart';
-import 'package:shadcn_ui/shadcn_ui.dart';
+import 'package:lucide_icons_flutter/lucide_icons.dart';
 import '../../../core/theme/app_theme.dart';
 import '../../../core/theme/app_spacing.dart';