curl --request POST \
  --url https://go.affixo.dev/v1/track/refund \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "external_id": "order_1234"
}
'

{
  "ok": true,
  "conversion_id": "<string>"
}