task-90(店铺中心): 实现店铺分组选项加载

新增 shop-group-model.ts(ShopManageGroupItemVo 下拉项解析) 并在
shop-manage-api.ts 增加 fetchShopManageGroups(GET /api/admin/shop-manages/groups，
后端限定普通管理员可访问分组)。

TDD: task-90.test.ts 8 用例先 RED 后 GREEN。

admin-frontend-vue/src/pages/shop/shop-manage-api.ts

@@ -1,9 +1,11 @@
-/** 店铺列表加载适配（任务 88）：GET /api/admin/shop-manages + 分页/筛选归一与解析。 */
+/** 店铺列表加载与分组选项适配（任务 88/90）：GET /api/admin/shop-manages(/groups) + 归一与解析。 */
 import { http } from '@/api/http'
 import { parseShopManagePage } from './shop-manage-model.ts'
+import { parseShopManageGroups } from './shop-group-model.ts'
 import {
   normalizeShopListParams,
   toShopManagePageQuery,
+  type ShopGroupOption,
   type ShopManageListParams,
   type ShopPageResult,
 } from './shop-dto.ts'
@@ -15,3 +17,11 @@ export async function fetchShopManageList(params: Partial<ShopManageListParams>
   const { data } = await http.get<unknown>(SHOP_MANAGE_ENDPOINT, { params: toShopManagePageQuery(normalized) })
   return parseShopManagePage(data)
 }
+
+export const SHOP_MANAGE_GROUPS_ENDPOINT = '/api/admin/shop-manages/groups'
+
+/** 加载店铺分组下拉选项（超级管理员取全部，普通管理员由后端限定可访问分组）。 */
+export async function fetchShopManageGroups(): Promise<ShopGroupOption[]> {
+  const { data } = await http.get<unknown>(SHOP_MANAGE_GROUPS_ENDPOINT)
+  return parseShopManageGroups(data)
+}