revert(c2c): 还原C2C市场页资产概览为原始状态

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/mining-app/lib/presentation/pages/c2c/c2c_market_page.dart

@@ -110,8 +110,8 @@ class _C2cMarketPageState extends ConsumerState<C2cMarketPage>
   }
 
   Widget _buildAssetOverview(BuildContext context, asset) {
+    final availableShares = asset?.availableShares ?? '0';
     final availableCash = asset?.availableCash ?? '0';
-    final frozenCash = asset?.frozenCash ?? '0';
 
     return Container(
       margin: const EdgeInsets.all(16),
@@ -150,12 +150,12 @@ class _C2cMarketPageState extends ConsumerState<C2cMarketPage>
                 crossAxisAlignment: CrossAxisAlignment.start,
                 children: [
                   Text(
-                    '冻结积分值',
+                    '可用积分值',
                     style: TextStyle(fontSize: 12, color: AppColors.textSecondaryOf(context)),
                   ),
                   const SizedBox(height: 4),
                   Text(
-                    formatAmount(frozenCash),
+                    formatAmount(availableCash),
                     style: const TextStyle(
                       fontSize: 18,
                       fontWeight: FontWeight.bold,