deriveAppStateBackupKey

Derives a 32-byte AES-256 key for the APP-STATE cloud backup from the wallet seed via HKDF-SHA256.

Like deriveDustBackupKey, this needs only the in-hand seed — no per-backup PRF/biometric — so app-state backups can run automatically in the background. Domain-separated from the dust-backup key (different salt + info) and from every other seed use.

Parameters