curl --request POST \
  --url https://app.autoposting.ai/api-proxy/billing/credits/purchase \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '{
  "amount": 100
}'

{
  "success": true,
  "data": {
    "purchased": 100,
    "newBalance": 550,
    "chargedAmount": 999,
    "currency": "usd"
  }
}