feat(cost-center): 卡券商品创建即生成渠道规则，补齐成本项预设

- 新建 tpv: 商品时自动写 third_party_voucher 规则，避免新卡券 SKU 停在待分类
- 成本项预设新增「第三方卡券采购成本」

apps/backend/src/services/cost-center/product-catalog-service.ts

@@ -16,6 +16,7 @@ import { nowIso } from '../../utils/time.js'
 import { normalizeMatchText, normalizeSkuSeriesEquivalence } from '../product-match/normalize.js'
 import { resolveSkuNameQuantity } from '../product-match/pricing.js'
 import { setAdminAffiliateProductPrice } from './affiliate-product-service.js'
+import { ensureVoucherRuleForSku } from '../fulfillment/channel-assign-service.js'
 import { syncAdminWorkProductRulePrice } from '../worker-platform/admin-worker-catalog-service.js'
 import {
   AFFILIATE_TASK_AGG_JOIN,
@@ -345,6 +346,10 @@ export async function createAdminProduct(payload: JsonObject, _session: AdminSes
       errorCode: 'cost_product_sku_exists',
     })
   }
+  // 卡券没有载体证据，创建商品时顺手把渠道规则补上，避免新 SKU 停在待分类。
+  if (canonicalSku.startsWith('tpv:')) {
+    await ensureVoucherRuleForSku(canonicalSku.slice(4))
+  }
   return { product: mapProduct(inserted) }
 }