- use Bech32 for witness v0 and Bech32m for witness v1+ in key_io
- update C++ bech32 tests and python segwit_addr framework
- realign key/address test vectors and fixtures to Palladium prefixes/params
- adjust chain-parameter-sensitive tests (maturity, BIP66/regtest, message verify)
- fix incorrect historical sha256 expected vector in unit tests
