Schema for webhook event logging and idempotency.

Every webhook received from payment providers is logged here to:

• Ensure idempotency (same event_id is never processed twice)
• Track processing status and errors
• Enable debugging and auditing
• Support retry logic for failed events

Idempotency

Before processing a webhook, we check if an event with the same provider + event_id combination exists. If it does, we skip processing and return success to prevent retries from provider.

Retry Logic

Failed events can be retried:

1. Provider sends retry (we check idempotency, process if not done)
2. Manual retry via admin interface
3. Background worker for events stuck in processing