feat(mining-app): 已销毁量去掉小数位显示

- format_utils.dart: 新增 formatIntWithCommas()，逗号千位分隔但不保留小数
- trading_page.dart: 已销毁量改用 formatIntWithCommas()

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

frontend/mining-app/lib/core/utils/format_utils.dart

@@ -44,6 +44,18 @@ String formatWithCommas(String? value) {
   }
 }
 
+/// 原始整数 + 逗号千位分隔（不保留小数）
+String formatIntWithCommas(String? value) {
+  if (value == null || value.isEmpty) return '0';
+  try {
+    final num = double.parse(value);
+    final formatter = NumberFormat('#,##0', 'zh_CN');
+    return formatter.format(num);
+  } catch (e) {
+    return '0';
+  }
+}
+
 String formatPercent(String? value, [int precision = 2]) {
   if (value == null || value.isEmpty) return '0%';
   try {

frontend/mining-app/lib/presentation/pages/trading/trading_page.dart

@@ -386,7 +386,7 @@ class _TradingPageState extends ConsumerState<TradingPage> {
               const SizedBox(width: 16),
               _buildMarketDataItem(
                 '已销毁量',
-                market != null ? formatWithCommas(market.blackHoleAmount) : null,
+                market != null ? formatIntWithCommas(market.blackHoleAmount) : null,
                 _red,
                 isLoading,
               ),