chore: use @scure/base for address encoders

[0xjc65eth]

This replaces the direct bech32 and bs58check address encoding dependencies with @scure/base, as suggested in #2241.

Notes:

• uses createBase58check(sha256) for base58check encoding/decoding
• keeps the existing mixed-case Bech32 error behavior covered by the current tests
• generated src/ from ts_src/ with the existing build script

Validation:

• npm test

Refs #2241