fix(kuaishou-industry): 修复电子凭证发货回调并发导致 807000 获取并发锁失败

同一 oid 的发货回调可能被多个来源并发调度（内存重试链 timer、worker_scan
兜底扫描、快手重复推送 send-code 后的再次调度），快手侧对同一 oid 有并发锁，
并发请求会返回 807000「获取并发锁失败」。

- runKuaishouIndustrySendCallbackForOid 增加进程内 in-flight 互斥，
  正在执行时其它调度直接跳过，由当前执行链路决定成功或按 backoff 重试
  （try/finally 保证所有 return 路径释放）
- listKuaishouIndustryVouchersForSendCallbackRetry 增加 maxAttempts 参数
  及 SQL 条件 COALESCE(send_callback_attempt_count,0) < ，缩小扫描集

apps/backend/src/repositories/kuaishou-industry-voucher-repo.ts

@@ -203,16 +203,18 @@ export async function listKuaishouIndustryVouchersByOid(
 
 export async function listKuaishouIndustryVouchersForSendCallbackRetry(
   limit = 100,
+  maxAttempts = 8,
 ): Promise<KuaishouIndustryVoucherRow[]> {
   const result = await query<KuaishouIndustryVoucherRow>(
     `
       SELECT *
       FROM kuaishou_industry_vouchers
       WHERE send_callback_status <> 'success'
+        AND COALESCE(send_callback_attempt_count, 0) < $2
       ORDER BY COALESCE(send_callback_sent_at, created_at) ASC, id ASC
       LIMIT $1
     `,
-    [normalizePositiveLimit(limit, 100)],
+    [normalizePositiveLimit(limit, 100), Math.max(1, Math.trunc(Number(maxAttempts) || 8))],
   )
 
   return result.rows
@@ -277,7 +279,9 @@ export async function listKuaishouIndustryVouchersForAdmin(
     where.push(`v.seller_id = $${params.length}`)
   }
 
-  const status = String(input.status || '').trim().toUpperCase()
+  const status = String(input.status || '')
+    .trim()
+    .toUpperCase()
   if (status) {
     params.push(status)
     where.push(`v.status = $${params.length}`)