POS6 Mini Program API

  GET  /api/health
  POST /api/login        { code, password }
  GET  /api/meta
  GET  /api/items        ?keyword=&cateId=&shopId=&status=&page=&pageSize=
  GET  /api/item/{id}
  GET  /api/invoices     ?from=YYYY-MM-DD&to=YYYY-MM-DD&shopId=&keyword=&tranType=&page=&pageSize=
  GET  /api/invoice/{id}