- Add HMAC SHA-256 signature verification for webhook payloads - Implement retry logic with delays (2s, 10s, 60s) and max 4 attempts - Add 20+ new events (total ~50 events) covering pages, blocks, users, etc. - Add API v2 endpoints for testing HMAC signature and retrying deliveries - Add comprehensive test suite for webhooks v2 functionality Generated by opencode.