curl --request POST \
  --url 'https://api.flashcat.cloud/calendar/create?app_key=' \
  --header 'Content-Type: application/json' \
  --data '
{
  "cal_name": "Production On-Call Calendar",
  "description": "Calendar for production on-call team",
  "timezone": "Asia/Shanghai",
  "workdays": [
    1,
    2,
    3,
    4,
    5
  ]
}
'

{
  "request_id": "01HK8XQE3Z7JM2NTFQ5YJ8P9R4",
  "data": {
    "cal_id": "cal.QiNvtdKs4Wj52kZhT3LafM",
    "cal_name": "API Test Calendar"
  }
}