fix(funds): 加固转账冲正、结算收付幂等与坏账核销

- 转入 main_site_timeout 等不可冲正场景直接拒绝，避免假结案
- payment_records / settlement_adjustments 增加 partial unique 索引
- 坏账核销行锁 + meta 幂等回放；补差单记录 result_bill_id
- 新增 FundOperationsHardeningTest 覆盖关键路径

app/Services/Wallet/LotteryTransferService.php

@@ -384,6 +384,14 @@ final class LotteryTransferService
             );
         }
 
+        if (! $this->isEligibleForReverse($locked)) {
+            throw new WalletOperationException(
+                'reverse_not_eligible',
+                ErrorCode::WalletExternalRejected->value,
+                422,
+            );
+        }
+
         if ($locked->direction === self::DIR_OUT) {
             $idempotentKey = 'reversal:'.$locked->transfer_no;
             $alreadyCredited = WalletTxn::query()
@@ -566,6 +574,20 @@ final class LotteryTransferService
             && $this->isEligibleForCompleteCredit($order);
     }
 
+    /** 后台冲正：转出 pending_reconcile 或转入 lottery_credit_failed 且主站已扣款。 */
+    public function isEligibleForReverse(TransferOrder $order): bool
+    {
+        if ($order->status !== self::ST_PENDING_RECONCILE) {
+            return false;
+        }
+
+        if ($order->direction === self::DIR_OUT) {
+            return true;
+        }
+
+        return $this->isEligibleForTransferInReverse($order);
+    }
+
     public function isEligibleForManualProcess(TransferOrder $order): bool
     {
         if (! in_array($order->status, [self::ST_PROCESSING, self::ST_FAILED, self::ST_PENDING_RECONCILE], true)) {