Zappr on Nostr: How one fingerprint becomes two keys in zappr: PRF(passkey, "NOSTR-SALT") > BIP32 > ...

How one fingerprint becomes two keys in zappr:
PRF(passkey, "NOSTR-SALT") > BIP32 > nsec
PRF(passkey, "WALLET-SALT") > BIP39 > Lightning wallet
No seed phrase stored anywhere. WebAuthn PRF runs entirely client-side we never touch the private key.