export private key from mnemonic

export_priv_key.rs

let hd_path = "m/44'/118'/0'/0/0".into_derivation_path().unwrap();
let secp = Secp256k1::new();
let pk = ExtendedPrivKey::new_master(Network::Bitcoin, seed)
        .unwrap()
        .derive_priv(&secp, hd_path)
        .unwrap();
let pubk = ExtendedPubKey::from_private(&secp, &pk);

let path = home::home_dir().unwrap().join(".orga-wallet").join("privkey");

std::fs::write(&path, _pk.private_key.to_bytes()).unwrap();

export_priv_key.ts

import { stringToPath, EnglishMnemonic, Bip39, Slip10, Slip10Curve } from "@cosmjs/crypto";
import os from "os";
import fs from "fs";
import path from "path";

const hdPath = stringToPath("m/44'/118'/0'/0/0");
const mnemonicChecked = new EnglishMnemonic(process.env.MNEMONIC);
const seed = await Bip39.mnemonicToSeed(mnemonicChecked);

const { privkey } = Slip10.derivePath(Slip10Curve.Secp256k1, seed, hdPath);

fs.writeFileSync(path.join(os.homedir(), ".orga-wallet/privkey"), privkey);