将 web-admin 从子模块改为仓库内普通目录，便于单仓克隆与维护。

Co-authored-by: Cursor <cursoragent@cursor.com>

web-admin/src/api/chinaRegion.ts

@@ -0,0 +1,15 @@
+import request from '@/utils/http'
+
+/** 与小程序端一致：value=区划代码，label=名称，children=下级 */
+export interface ChinaRegionTreeNode {
+  value: string
+  label: string
+  children?: ChinaRegionTreeNode[]
+}
+
+/** 运营端：数据源 bas_china_region */
+export function fetchChinaRegionTree() {
+  return request.get<{ tree: ChinaRegionTreeNode[] }>({
+    url: '/web/admin/china-region-tree'
+  })
+}