[Placeholder] Add Purchase ID to Download Webhook Payload

[rednex]

Currently, the download webhook triggered upon a resource download does not include the purchase ID, which limits the ability to generate unique license keys per purchase. Adding the purchase ID to the webhook payload would enable developers to properly associate activations with specific purchases and better manage license key deliveries. This would especially benefit stocked key systems and improve automation for resource sellers.

Please consider enhancing the webhook data to include purchase_id alongside the current information.