fix(mining-app): 分配记录时间压缩防溢出 + 剩余积分股扣除销毁量

1. 分配记录页面：
   - 时间格式从完整时间戳压缩为 "YY/MM/DD HH:mm:ss"，节省空间
   - 积分股字号从18缩至13，字体改为monospace便于对齐
   - 外层加 Flexible 防止超出屏幕右边界

2. 兑换页面剩余积分股：
   - 公式从 totalShares - totalMined
     改为 totalShares - totalMined - blackHoleAmount
   - 即：总量 - 已分配 - 已销毁 = 真正的剩余可分配量

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

frontend/mining-app/lib/presentation/pages/profile/mining_records_page.dart

@@ -216,20 +216,23 @@ class _MiningRecordsListPageState extends ConsumerState<MiningRecordsListPage> {
             mainAxisAlignment: MainAxisAlignment.spaceBetween,
             children: [
               Text(
-                record.distributionMinute,
+                _shortTime(record.distributionMinute),
                 style: const TextStyle(
-                  fontSize: 14,
+                  fontSize: 12,
                   fontWeight: FontWeight.w500,
                   color: _darkText,
-                  fontFamily: 'monospace',
                 ),
               ),
-              Text(
+              Flexible(
+                child: Text(
                   '+${formatDecimal(record.shareAmount, 13)}',
                   style: const TextStyle(
-                  fontSize: 18,
+                    fontSize: 13,
                     fontWeight: FontWeight.bold,
                     color: _green,
+                    fontFamily: 'monospace',
+                  ),
+                  textAlign: TextAlign.right,
                 ),
               ),
             ],
@@ -290,6 +293,24 @@ class _MiningRecordsListPageState extends ConsumerState<MiningRecordsListPage> {
     );
   }
 
+  /// 压缩时间显示：'2026-03-02 17:24:00' → '26/03/02 17:24'
+  String _shortTime(String time) {
+    // 去掉秒和毫秒部分，截短年份
+    final t = time.replaceAll('T', ' ').split('.').first; // 去毫秒
+    try {
+      final dt = DateTime.parse(t);
+      final y = (dt.year % 100).toString().padLeft(2, '0');
+      final m = dt.month.toString().padLeft(2, '0');
+      final d = dt.day.toString().padLeft(2, '0');
+      final h = dt.hour.toString().padLeft(2, '0');
+      final min = dt.minute.toString().padLeft(2, '0');
+      final s = dt.second.toString().padLeft(2, '0');
+      return '$y/$m/$d $h:$min:$s';
+    } catch (_) {
+      return time.length > 16 ? time.substring(0, 16) : time;
+    }
+  }
+
   String _formatPercent(String ratio) {
     try {
       final value = double.parse(ratio);

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

@@ -362,7 +362,8 @@ class _TradingPageState extends ConsumerState<TradingPage> {
                 market != null
                     ? formatCompact(
                         (Decimal.parse(market.totalShares) -
-                                Decimal.parse(market.totalMined))
+                                Decimal.parse(market.totalMined) -
+                                Decimal.parse(market.blackHoleAmount))
                             .toString(),
                         precision: 4)
                     : null,