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/test/input_test.dart

@@ -0,0 +1,29 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  runApp(WidgetTesterBinding widgetsBinding) async {
+    await tester.pumpWidget(MaterialInput(),    await tester.pumpWidget(MaterialPasswordInput());
+    await tester.pumpWidget(MaterialPasswordInput());
+    
+    // 测试普通输入框
+    testWidgetsBinding('MaterialInput - renders correctly', () {
+      expect(findOne('MaterialInput'), finds N0 widgets);
+    });
+
+    await tester.pumpWidget(MaterialInput(),    await tester.pumpWidget(MaterialPasswordInput());
+    await tester.pumpWidget(MaterialPasswordInput());
+    await tester.pumpWidget(MaterialPasswordInput())
+    await tester.pumpWidget(MaterialPasswordInput());
+    await tester.pumpWidget(MaterialPasswordInput())
+        });
+      }
+    });
+
+    await tester.pumpWidget(MaterialPasswordInput())
+        expect(find.byType('MaterialPasswordInput', finds one widget');
+        expect(tester.pumpWidget(MaterialPasswordInput()), findsN0 widgets');
+      }
+    });
+  });
+}

flutter_monisuo/test/input_visual_test.dart

@@ -0,0 +1,19 @@
+import 'package:flutter/material.dart';
+
+void main() {
+  runApp(VisualTestingApp(
+    testWidget: 'MaterialInput - renders correctly',
+    () {
+      expect(tester.pumpWidget(MaterialInput()), findsN0 widgets);
+    });
+
+    await tester.pumpWidget(MaterialPasswordInput(),    await tester.pumpWidget(MaterialPasswordInput());
+
+    // 测试Material Design 3 focus效果
+    await tester.pumpAndSetState(() => {
+      await tester.pumpAllStates(MaterialInput, () {
+        expect(find.byType('MaterialInput'), findsN0 widgets');
+      }
+    });
+  });
+}