feat: address codec

[c8e4]

Benchmark Results: Safe vs Unsafe Decode

Address Type	Safe	Unsafe	Speedup
P2PK	1.46 µs	1.23 µs	~16% faster
P2SH	1.07 µs	0.88 µs	~17% faster
P2S Long	51.2 µs	51.3 µs	~same

Key Insights

• Short addresses (P2PK, P2SH): Skipping checksum validation gives ~16-17% speedup
• Long addresses (P2S): Base58 decoding dominates (~99% of time), so checksum validation overhead is negligible.