fix(c2c): MATCHED/PAID订单过期后自动恢复为新PENDING订单

当部分成交的订单过期时，将过期数量恢复到市场：
- BUY单过期：直接为maker创建新PENDING BUY单
- SELL单过期：检查maker余额，重新冻结后创建新PENDING SELL单
- 恢复失败不影响过期流程（仅记录日志）

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

backend/services/trading-service/src/application/services/c2c.service.ts

@@ -747,8 +747,64 @@ export class C2cService {
       });
 
       this.logger.log(`C2C订单已过期: ${freshOrder.orderNo}, 原状态: ${freshOrder.status}`);
+
+      // MATCHED/PAID 订单过期后，将数量退还为新的 PENDING 订单（恢复到市场）
+      if (freshOrder.status === C2C_ORDER_STATUS.MATCHED || freshOrder.status === C2C_ORDER_STATUS.PAID) {
+        await this.restoreExpiredOrder(freshOrder, quantityDecimal);
+      }
     } finally {
       await this.redis.releaseLock(lockKey, lockValue);
     }
   }
+
+  /**
+   * 过期订单恢复：为 maker 重新创建一个 PENDING 订单
+   * 将过期的成交数量退还到市场，让其他用户可以继续接单
+   */
+  private async restoreExpiredOrder(expiredOrder: C2cOrderEntity, quantityDecimal: Decimal): Promise<void> {
+    try {
+      const priceDecimal = new Decimal(expiredOrder.price);
+      const totalAmountDecimal = priceDecimal.mul(quantityDecimal);
+
+      // SELL 订单需要重新冻结 maker 的积分值
+      if (expiredOrder.type === C2C_ORDER_TYPE.SELL) {
+        const makerAccount = await this.tradingAccountRepository.findByAccountSequence(expiredOrder.makerAccountSequence);
+        if (!makerAccount) {
+          this.logger.warn(`过期恢复: maker ${expiredOrder.makerAccountSequence} 账户不存在，跳过恢复`);
+          return;
+        }
+        const quantityMoney = new Money(quantityDecimal);
+        if (makerAccount.availableCash.isLessThan(quantityMoney)) {
+          this.logger.warn(`过期恢复: maker ${expiredOrder.makerAccountSequence} 可用余额不足 (需要 ${quantityDecimal}, 可用 ${makerAccount.availableCash})，跳过恢复`);
+          return;
+        }
+        await this.tradingAccountRepository.freezeCash(expiredOrder.makerAccountSequence, quantityDecimal);
+      }
+
+      // 创建新的 PENDING 订单
+      const restoreOrderNo = this.generateOrderNo();
+      await this.c2cOrderRepository.create({
+        orderNo: restoreOrderNo,
+        type: expiredOrder.type as any,
+        makerAccountSequence: expiredOrder.makerAccountSequence,
+        makerUserId: expiredOrder.makerUserId ?? undefined,
+        makerPhone: expiredOrder.makerPhone ?? undefined,
+        makerNickname: expiredOrder.makerNickname ?? undefined,
+        price: expiredOrder.price,
+        quantity: quantityDecimal.toString(),
+        totalAmount: totalAmountDecimal.toString(),
+        paymentMethod: expiredOrder.type === C2C_ORDER_TYPE.SELL ? (expiredOrder.paymentMethod ?? undefined) : undefined,
+        paymentAccount: expiredOrder.type === C2C_ORDER_TYPE.SELL ? (expiredOrder.paymentAccount ?? undefined) : undefined,
+        paymentQrCode: expiredOrder.type === C2C_ORDER_TYPE.SELL ? (expiredOrder.paymentQrCode ?? undefined) : undefined,
+        paymentRealName: expiredOrder.type === C2C_ORDER_TYPE.SELL ? (expiredOrder.paymentRealName ?? undefined) : undefined,
+        sellerKavaAddress: expiredOrder.sellerKavaAddress,
+        remark: expiredOrder.remark ?? undefined,
+      });
+
+      this.logger.log(`过期恢复: 订单 ${expiredOrder.orderNo} 已恢复为新 PENDING 订单 ${restoreOrderNo}, 数量: ${quantityDecimal}`);
+    } catch (error) {
+      this.logger.error(`过期恢复失败: ${expiredOrder.orderNo}`, error);
+      // 恢复失败不影响过期流程，只记录日志
+    }
+  }
 }