curl --request POST \
  --url https://api.zangsho.com/v1/subscriptions/events \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "customer_email": "customer@example.com",
  "event_type": "upgrade",
  "old_amount": "500.00",
  "new_amount": "990.00",
  "amount_change": "490.00",
  "old_plan": "Basic",
  "new_plan": "Pro",
  "occurred_at": "2026-01-09T00:00:00Z"
}
'

{
  "data": {
    "id": 123,
    "customer_id": 123,
    "event_type": "created",
    "source": "api",
    "old_amount": "<string>",
    "new_amount": "<string>",
    "amount_change": "<string>",
    "old_plan": "<string>",
    "new_plan": "<string>",
    "occurred_at": "2023-11-07T05:31:56Z",
    "created_at": "2023-11-07T05:31:56Z"
  }
}