refactor(finance): 成本模型与履约方式正交，拆分成本中心巨型文件

后端：
- 删除 services/admin/admin-cost-center-service.ts（4,248 行），拆为
  services/cost-center/ 下 5 个模块：
  cost-center-shared（类型/枚举/归一化/映射/costModelScopeSql）、
  cost-center-overview（总览与选项）、
  product-catalog（商品与渠道映射）、
  template-bootstrap（模板引导、自动发货同步、工单证据回填）、
  cost-definition（成本项/版本/异常/预览/快照）
- cost_items.carrier_type / cost_type 改为单一 cost_model；专属模型只对
  对应履约方式生效，通用模型对所有履约方式生效
- cost_snapshots / cost_exceptions 删除载体列；按履约方式筛异常改用
  IN 半连接（248k 异常下 EXISTS 逐行回表 2.7s -> 170ms）
- sales_daily_facts.carrier_type -> fulfillment_mode
- 人工支出按 cost_model 归类；履约方式只读 order_items.fulfillment_mode
- 移除 syncOpenCostExceptionCarrierTypes：异常表已无载体列可同步

前端：
- AdminCostCenterPage.tsx（2,887 行 -> 18 行转发），拆为
  pages/admin/cost-center/ 下 8 个 Panel + shared + CostCenterContext
- CostCarrierType 删除；新增 FulfillmentMode / ProductSource / CostModel
- 销售毛利页 carrierType -> fulfillmentMode

同步补两个索引：idx_order_items_fulfillment_id（异常半连接）、
idx_work_categories_name（商品目录分类 lateral join）。

apps/backend/src/routes/admin/cost-center.ts

@@ -2,37 +2,43 @@ import type { Request } from 'express'
 import { Router } from 'express'
 
 import {
-  applyAdminTemplateProductBootstrap,
-  backfillAdminAffiliateDashSkus,
-  backfillAdminNormalizedQuantities,
-  backfillAdminProductMappings,
-  backfillAdminWorkOrderProductSkus,
-  createAdminChannelMapping,
+  getAdminCostCenterOptions,
+  getAdminCostCenterOverview,
+} from '../../services/cost-center/cost-center-overview-service.js'
+import {
   createAdminCostItem,
   createAdminCostSnapshot,
   createAdminCostVersion,
-  createAdminProduct,
-  deleteAdminChannelMapping,
   deleteAdminCostItem,
   deleteAdminCostVersion,
-  deleteAdminProduct,
-  getAdminCostCenterOptions,
-  getAdminCostCenterOverview,
-  listAdminChannelMappings,
   listAdminCostExceptions,
   listAdminCostItems,
   listAdminCostVersions,
-  listAdminProducts,
   previewAdminCost,
-  previewAdminTemplateProductBootstrap,
   resolveAdminCostException,
   retireAdminCostVersion,
+  updateAdminCostItem,
+} from '../../services/cost-center/cost-definition-service.js'
+import {
+  backfillAdminNormalizedQuantities,
+  backfillAdminProductMappings,
+  createAdminChannelMapping,
+  createAdminProduct,
+  deleteAdminChannelMapping,
+  deleteAdminProduct,
+  listAdminChannelMappings,
+  listAdminProducts,
+  updateAdminChannelMapping,
+  updateAdminProduct,
+} from '../../services/cost-center/product-catalog-service.js'
+import {
+  applyAdminTemplateProductBootstrap,
+  backfillAdminAffiliateDashSkus,
+  backfillAdminWorkOrderProductSkus,
+  previewAdminTemplateProductBootstrap,
   syncAdminAffiliateDashProducts,
   syncAdminWorkOrderTemplateCostVersions,
-  updateAdminChannelMapping,
-  updateAdminCostItem,
-  updateAdminProduct,
-} from '../../services/admin/admin-cost-center-service.js'
+} from '../../services/cost-center/template-bootstrap-service.js'
 import type { AdminSession } from '../../services/admin/admin-auth-service.js'
 import {
   syncActualWorkOrderCostSnapshots,

apps/backend/src/routes/admin/worker-platform/config.ts

@@ -1,6 +1,6 @@
 import { Router } from 'express'
 import { setHttpCache } from '../../../middleware/http-cache.js'
-import { syncAdminWorkOrderTemplateCostVersions } from '../../../services/admin/admin-cost-center-service.js'
+import { syncAdminWorkOrderTemplateCostVersions } from '../../../services/cost-center/template-bootstrap-service.js'
 
 import {
   deleteAdminWorkCategory,