Function parse_evm_spec 

pub fn parse_evm_spec(spec: &str) -> SpecId

Parse an EVM hardfork spec name (e.g. from TOML config) into a revm SpecId.

Accepts revm’s canonical names (e.g. "Cancun", "Shanghai", "Prague") case-insensitively. Falls back to SpecId::CANCUN for unrecognized values.