Cancel campaign

curl --request POST \
  --url https://api.vidjutsu.ai/v1/campaigns/cancel \
  --header 'Content-Type: application/json' \
  --header 'X-Api-Key: <api-key>' \
  --data '
{
  "campaignId": "<string>"
}
'

{
  "campaignId": "<string>",
  "status": "cancelled",
  "creditsRefunded": 123
}