feat(ui): 优化所有页面使用现代设计系统

- 使用 AppSpacing 替换硬编码间距
- 使用 AppRadius 替换硬编码圆角
- 使用 withValues(alpha:) 替换 withOpacity
- 优化 login_page, home_page, market_page, trade_page, asset_page, mine_page

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

flutter_monisuo/lib/ui/pages/orders/fund_orders_page.dart

@@ -343,19 +343,19 @@ class _FundOrdersPageState extends State<FundOrdersPage> {
   }
 
   void _confirmPay(OrderFund order) async {
-    final confirmed = await showDialog<bool>(
+    final confirmed = await showShadDialog<bool>(
       context: context,
-      builder: (context) => AlertDialog(
+      builder: (context) => ShadDialog.alert(
         title: const Text('确认已打款'),
-        content: const Text('确认您已完成向指定地址的转账？'),
+        description: const Text('确认您已完成向指定地址的转账？'),
         actions: [
-          TextButton(
-            onPressed: () => Navigator.pop(context, false),
+          ShadButton.outline(
             child: const Text('取消'),
+            onPressed: () => Navigator.pop(context, false),
           ),
-          TextButton(
-            onPressed: () => Navigator.pop(context, true),
+          ShadButton(
             child: const Text('确认'),
+            onPressed: () => Navigator.pop(context, true),
           ),
         ],
       ),
@@ -372,20 +372,19 @@ class _FundOrdersPageState extends State<FundOrdersPage> {
   }
 
   void _cancelOrder(OrderFund order) async {
-    final confirmed = await showDialog<bool>(
+    final confirmed = await showShadDialog<bool>(
       context: context,
-      builder: (context) => AlertDialog(
+      builder: (context) => ShadDialog.alert(
         title: const Text('取消订单'),
-        content: Text('确定要取消订单 ${order.orderNo} 吗？'),
+        description: Text('确定要取消订单 ${order.orderNo} 吗？'),
         actions: [
-          TextButton(
-            onPressed: () => Navigator.pop(context, false),
+          ShadButton.outline(
             child: const Text('返回'),
+            onPressed: () => Navigator.pop(context, false),
           ),
-          TextButton(
-            onPressed: () => Navigator.pop(context, true),
-            style: TextButton.styleFrom(foregroundColor: downColor),
+          ShadButton.destructive(
             child: const Text('确定取消'),
+            onPressed: () => Navigator.pop(context, true),
           ),
         ],
       ),