- Expose more key derivations to apps via new BackupKey class, as well as additional APIs on MessageBackupKey and AccountEntropyPool. - Adjust backup ID derivation from a BackupKey once more (hopefully the last time). - iOS: Make incremental MAC chunk size value accessible - Node: Properly re-export BackupCredentialType through zkgroup module - Internal change: Use new websocket event handler for attested connections. This should not produce any difference in behavior, but if any is observed this might be the cause.