curl --request POST \
  --url https://mag3nt.com/api/cards/{id}/fund \
  --header 'Authorization: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '{
  "amount": 25
}'

{
  "success": true,
  "card_id": "<string>",
  "added": 123,
  "new_limit": 123
}