feat(cost-center): 渠道映射改为诊断优先，新增未归一队列

- 顶部统计卡：标准商品 / 映射 / 未归一订单项 / 未归一 SKU 组
- 新增「未归一」队列：按来源+店铺+平台SKU+履约方式聚合，行内建映射并预填
- 目录表从 7 列精简到 4 列，匹配方式移入展开明细
- 回填订单项后自动把已归一的 product_mapping_missing 异常收口
- 新增 /cost-center/mappings/diagnostics 与 /mappings/unmapped，按履约方式拆分聚合避免全表扫描

apps/frontend/src/services/admin/cost-center.ts

@@ -1,5 +1,6 @@
 import { apiDelete, apiGet, apiPatch, apiPost } from '@/lib/http'
 import type {
+  ChannelMappingDiagnostics,
   ChannelProductMapping,
   ChannelProductMappingListResult,
   CostCenterOptions,
@@ -27,6 +28,7 @@ import type {
   ProductCatalogListResult,
   TemplateProductBootstrapPreview,
   TemplateProductBootstrapResult,
+  UnmappedMappingGroupListResult,
 } from '@/types/admin'
 
 export function fetchAdminCostCenterOverview() {
@@ -130,6 +132,17 @@ export function fetchAdminChannelProductMappings(params?: Record<string, unknown
   return apiGet<ChannelProductMappingListResult>('/api/v1/admin/cost-center/mappings', params)
 }
 
+export function fetchAdminChannelMappingDiagnostics(params?: Record<string, unknown>) {
+  return apiGet<ChannelMappingDiagnostics>('/api/v1/admin/cost-center/mappings/diagnostics', params)
+}
+
+export function fetchAdminUnmappedMappingGroups(params?: Record<string, unknown>) {
+  return apiGet<UnmappedMappingGroupListResult>(
+    '/api/v1/admin/cost-center/mappings/unmapped',
+    params,
+  )
+}
+
 export function createAdminChannelProductMapping(payload: Record<string, unknown>) {
   return apiPost<{ mapping: ChannelProductMapping }>('/api/v1/admin/cost-center/mappings', payload)
 }
@@ -153,6 +166,7 @@ export function deleteAdminChannelProductMapping(mappingId: number) {
 export function backfillAdminProductMappings(payload: Record<string, unknown>) {
   return apiPost<{
     updatedCount: number
+    resolvedExceptionCount: number
     limit: number
     batches: number
     remainingCount: number