curl --request GET \
  --url https://api.steppay.kr/api/v1/customers/{id} \
  --header 'Secret-Token: <api-key>'

{
  "id": 1,
  "status": "NORMAL",
  "username": "test@gmail.com",
  "name": "테스트 고객",
  "email": "test@gmail.com",
  "phone": "01012345678",
  "orderCount": 0,
  "totalPurchasedPrice": 0,
  "shipping": null,
  "orders": [],
  "subscriptions": [],
  "paymentMethods": [],
  "code": "customer_AbCdEfGhI",
  "marketingSms": false,
  "marketingEmail": false,
  "marketingKakao": false,
  "attributes": {},
  "createdAt": "9999-01-01T00:00:00",
  "additionalRecipients": []
}