Webhook headers

Every Probatix webhook delivery includes the following headers.

Header	Description
`X-Probatix-Topic`	The event type. Its value identifies the delivered event and is shown on the relevant webhook page.
`X-Probatix-Webhook-Version`	The webhook contract version. Current value: `v1`.
`X-Probatix-Webhook-Occurred-At`	The time the event occurred, formatted as an ISO 8601 date-time.
`X-Probatix-Webhook-Id`	A unique UUID delivery identifier for deduplication.
`X-Probatix-Hmac-SHA256`	A Base64-encoded HMAC-SHA256 signature of the raw request body. Verify it with your webhook signing secret before processing the payload.