fix: 修复复制地址提示层级问题，改用 toast 提示

- 创建统一的 ToastUtils 工具类
- 使用 BotToast.showCustomText 确保显示在所有弹窗之上
- 更新三处复制地址的代码使用新的 toast 方案
- 添加阴影效果提升视觉层次
- 支持成功/错误/警告等多种提示类型

flutter_monisuo/lib/ui/pages/asset/asset_page.dart

@@ -1,10 +1,12 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:shadcn_ui/shadcn_ui.dart';
+import 'package:bot_toast/bot_toast.dart';
 import 'package:provider/provider.dart';
 import 'package:google_fonts/google_fonts.dart';
 import '../../../core/theme/app_color_scheme.dart';
 import '../../../core/theme/app_spacing.dart';
+import '../../../core/utils/toast_utils.dart';
 import '../../../providers/asset_provider.dart';
 import '../../../providers/auth_provider.dart';
 import '../../shared/ui_constants.dart';
@@ -862,9 +864,7 @@ class _WalletAddressCard extends StatelessWidget {
               GestureDetector(
                 onTap: () {
                   Clipboard.setData(ClipboardData(text: address));
-                  ScaffoldMessenger.of(context).showSnackBar(
-                    const SnackBar(content: Text('地址已复制到剪贴板')),
-                  );
+                  ToastUtils.show('地址已复制到剪贴板');
                 },
                 child: Container(
                   padding: EdgeInsets.all(AppSpacing.xs),

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

@@ -1,10 +1,12 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:shadcn_ui/shadcn_ui.dart';
+import 'package:bot_toast/bot_toast.dart';
 import 'package:provider/provider.dart';
 import 'package:google_fonts/google_fonts.dart';
 import '../../../core/theme/app_color_scheme.dart';
 import '../../../core/theme/app_spacing.dart';
+import '../../../core/utils/toast_utils.dart';
 import '../../../data/models/account_models.dart';
 import '../../../data/services/asset_service.dart';
 import '../../../data/services/bonus_service.dart';
@@ -1346,9 +1348,7 @@ class _WalletAddressCard extends StatelessWidget {
               GestureDetector(
                 onTap: () {
                   Clipboard.setData(ClipboardData(text: address));
-                  ScaffoldMessenger.of(context).showSnackBar(
-                    const SnackBar(content: Text('地址已复制到剪贴板')),
-                  );
+                  ToastUtils.show('地址已复制到剪贴板');
                 },
                 child: Container(
                   padding: EdgeInsets.all(AppSpacing.xs),

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

@@ -1,7 +1,9 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:shadcn_ui/shadcn_ui.dart';
+import 'package:bot_toast/bot_toast.dart';
 import 'package:provider/provider.dart';
+import '../../../core/utils/toast_utils.dart';
 import '../../../providers/asset_provider.dart';
 import '../../../data/models/order_models.dart';
 
@@ -245,9 +247,7 @@ class _FundOrdersPageState extends State<FundOrdersPage> {
                 GestureDetector(
                   onTap: () {
                     Clipboard.setData(ClipboardData(text: order.walletAddress!));
-                    ScaffoldMessenger.of(context).showSnackBar(
-                      const SnackBar(content: Text('地址已复制')),
-                    );
+                    ToastUtils.show('地址已复制');
                   },
                   child: Icon(LucideIcons.copy, size: 14, color: Colors.grey[600]),
                 ),