ECDSA Signature Parser
Parse ECDSA signatures into r, s, v components
r: The x-coordinate of a random point on the elliptic curve (32 bytes)
s: The signature proof value (32 bytes)
v: Recovery ID that helps recover the public key (1 byte, optional)
Common v values:
- 27 or 28: Legacy Ethereum signatures
- 0 or 1: Modern EIP-2098 compact signatures
- 35+: EIP-155 signatures with chain ID