Add Bismuth (BIS, SLIP-0044=209) cryptocurrency support with tests

[alias-bitsignal]

Main Info

• Added Bismuth (BIS) cryptocurrency support (SLIP-0044 = 209), based on the secp256k1 curve.
• Implemented multi-byte Base58Check version prefixes for Bismuth addresses.
• Added full test coverage (tests/test_bismuth.py) — all 7/7 tests passing.
• Integrated into hdwallet/init.py for export and discovery.
• Verified on Python 3.8, 3.9, and 3.10 — no compatibility issues found.

Example Usage (BIP-44)

from hdwallet import HDWallet
from hdwallet.cryptocurrencies import Bismuth
from hdwallet.hds import BIP44HD
from hdwallet.mnemonics import BIP39Mnemonic
from hdwallet.derivations import BIP44Derivation, CHANGES

MNEMONIC = "abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about"

hdwallet = (
    HDWallet(cryptocurrency=Bismuth, hd=BIP44HD, network=Bismuth.NETWORKS.MAINNET)
    .from_mnemonic(BIP39Mnemonic(MNEMONIC))
    .from_derivation(
        BIP44Derivation(
            coin_type=Bismuth.COIN_TYPE,  # 209
            account=0,
            change=CHANGES.EXTERNAL_CHAIN,
            address=(0, 1),
        )
    )
)

leaf = max(hdwallet.dumps(exclude={"root", "indexes"}), key=lambda r: r["at"]["path"].count("/"))
print("Path:", leaf["at"]["path"])
print("Address:", leaf["address"])

Example Output of the above Code

Path: m/44'/209'/0'/0/0
Address: Bis1LenEHPex4WwY3BLxFGRmxNtsvKqgxkSbh

Verification

• pytest -q tests/test_bismuth.py → 7 passed
• Address derivation matches Bismuth mainnet prefix (Bis1)
• Testnet address derivations prefixed with tBis
• Correct Base58Check encoding/decoding with multi-byte version guard
• Address validator correctly accepts and rejects checksums
• Compatible with HDWallet API and BIP44Derivation

Files Changed

• hdwallet/cryptocurrencies/bismuth.py → new file
• hdwallet/cryptocurrencies/__init__.py → added Bismuth export
• tests/test_bismuth.py → new test suite

Notes
Bismuth support now aligns with the standard BIP-44 hierarchy:
m / 44' / 209' / 0' / 0 / 0