curl --request POST \
  --url https://app.autoposting.ai/api-proxy/billing/verify-checkout \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "sessionId": "cs_abc123"
}
'

{
  "success": true,
  "data": {
    "status": "trialing",
    "trialEnd": "2024-01-04T00:00:00Z",
    "planId": "plan_pro"
  }
}