(caveat: that was just an experimental branch that I never intended to PR into the main repo. I do want to pull over the bip39 mnemonic-to-nsec derivation, but the other nostr-related functions don't really make sense in an air-gapped signer. It'd be different if nip26 had become widely adopted, but alas, good key management in nostr was not to be (not that nip26 was perfect either, though))