fix(partner): grant store staff open/close and media permissions by default

Default new sub-accounts to store:create+store:manage, backfill empty permissions on /partner/me, and treat legacy store staff as allowed to mutate.

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

packages/shared-types/src/city-partner.ts

@@ -89,3 +89,9 @@ export const PARTNER_PERMISSION_LABELS: Record<PartnerPermissionKey, string> = {
   'store:create': '开店管理',
   'order:view': '订单查看',
 };
+
+/** 门店类子账号默认权限：录入、开闭店、维护资料 */
+export const DEFAULT_PARTNER_STORE_STAFF_PERMISSIONS: PartnerPermissionKey[] = [
+  'store:create',
+  'store:manage',
+];