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/shared/modern_bottom_sheet.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
-import 'package:shadcn_ui/shadcn_ui.dart';
+import 'package:lucide_icons_flutter/lucide_icons.dart';
 import '../../core/theme/app_spacing.dart';
+import '../../core/theme/app_theme.dart';
 
 /// 現代底部抽屜模板 - 基於 modernization-v2.md 規範
 ///
@@ -100,17 +101,19 @@ class ModernBottomSheet extends StatelessWidget {
           Row(
             children: [
               Expanded(
-                child: ShadButton.outline(
+                child: OutlinedButton(
                   onPressed: () => Navigator.of(context).pop(0),
                   child: Text(cancelText),
                 ),
               ),
               const SizedBox(width: AppSpacing.md),
               Expanded(
-                child: ShadButton(
-                  backgroundColor: isDestructive
-                    ? ShadTheme.of(context).colorScheme.destructive
-                    : null,
+                child: ElevatedButton(
+                  style: ElevatedButton.styleFrom(
+                    backgroundColor: isDestructive
+                        ? Theme.of(context).colorScheme.error
+                        : null,
+                  ),
                   onPressed: () => Navigator.of(context).pop(1),
                   child: Text(confirmText),
                 ),
@@ -125,12 +128,12 @@ class ModernBottomSheet extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final theme = ShadTheme.of(context);
+    final theme = Theme.of(context);
     final bottomPadding = MediaQuery.of(context).padding.bottom;
 
     return Container(
       decoration: BoxDecoration(
-        color: theme.colorScheme.card,
+        color: theme.colorScheme.surfaceContainer,
         borderRadius: const BorderRadius.vertical(
           top: Radius.circular(AppRadius.xxl),
         ),
@@ -164,21 +167,21 @@ class ModernBottomSheet extends StatelessWidget {
     );
   }
 
-  Widget _buildDragHandle(ShadThemeData theme) {
+  Widget _buildDragHandle(ThemeData theme) {
     return Center(
       child: Container(
         width: 40,
         height: 4,
         margin: const EdgeInsets.only(bottom: AppSpacing.md),
         decoration: BoxDecoration(
-          color: theme.colorScheme.muted,
+          color: theme.colorScheme.outline,
           borderRadius: BorderRadius.circular(2),
         ),
       ),
     );
   }
 
-  Widget _buildHeader(BuildContext context, ShadThemeData theme) {
+  Widget _buildHeader(BuildContext context, ThemeData theme) {
     return Padding(
       padding: const EdgeInsets.only(bottom: AppSpacing.md),
       child: Row(
@@ -187,7 +190,7 @@ class ModernBottomSheet extends StatelessWidget {
           Expanded(
             child: titleWidget ?? Text(
               title!,
-              style: theme.textTheme.h3.copyWith(
+              style: AppTextStyles.headlineSmall(context).copyWith(
                 fontWeight: FontWeight.w600,
               ),
             ),
@@ -202,7 +205,7 @@ class ModernBottomSheet extends StatelessWidget {
               child: Icon(
                 LucideIcons.x,
                 size: 20,
-                color: theme.colorScheme.mutedForeground,
+                color: theme.colorScheme.onSurfaceVariant,
               ),
             ),
         ],
@@ -219,7 +222,7 @@ class _ActionList extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final theme = ShadTheme.of(context);
+    final theme = Theme.of(context);
 
     return Column(
       children: actions.asMap().entries.map((entry) {
@@ -229,7 +232,7 @@ class _ActionList extends StatelessWidget {
         return Column(
           children: [
             if (index > 0 && actions[index - 1].isDivider)
-              Divider(color: theme.colorScheme.border, height: 1),
+              Divider(color: theme.colorScheme.outline, height: 1),
             _ActionTile(action: action),
           ],
         );
@@ -246,7 +249,7 @@ class _ActionTile extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    final theme = ShadTheme.of(context);
+    final theme = Theme.of(context);
 
     return InkWell(
       onTap: () {
@@ -266,8 +269,8 @@ class _ActionTile extends StatelessWidget {
                 action.icon,
                 size: 20,
                 color: action.isDestructive
-                    ? theme.colorScheme.destructive
-                    : theme.colorScheme.foreground,
+                    ? theme.colorScheme.error
+                    : theme.colorScheme.onSurface,
               ),
               const SizedBox(width: AppSpacing.md),
             ],
@@ -277,8 +280,8 @@ class _ActionTile extends StatelessWidget {
                 style: TextStyle(
                   fontSize: 16,
                   color: action.isDestructive
-                      ? theme.colorScheme.destructive
-                      : theme.colorScheme.foreground,
+                      ? theme.colorScheme.error
+                      : theme.colorScheme.onSurface,
                 ),
               ),
             ),