curl --request POST \
  --url https://core-api.getaptly.com/api/board/{boardId}/{cardId}/file \
  --header 'Content-Type: multipart/form-data' \
  --header 'x-token: <api-key>' \
  --form file='@example-file'

{
  "data": {
    "fileId": "<string>",
    "name": "<string>",
    "size": 123,
    "type": "<string>"
  }
}