curl --request POST \
  --url https://api.kit.com/v4/tags \
  --header 'Content-Type: application/json' \
  --header 'X-Kit-Api-Key: <api-key>' \
  --data '{
  "name": "Completed"
}'

{
  "tag": {
    "id": 3601,
    "name": "Completed",
    "created_at": "2025-06-06T19:00:02Z"
  }
}