Derives the 64-byte BIP-39 seed from a mnemonic and optional passphrase.
Parameters
mnemonic: string
passphrase: string = ''
Returns Uint8Array
Remarks
Normalizes (NFKD) and checks the word count only; wordlist membership and the checksum are not
verified, so validate the phrase first if it came from a user. Same name and semantics as
@scure/bip39.
Derives the 64-byte BIP-39 seed from a mnemonic and optional passphrase.