Function parse_sign_target 

pub fn parse_sign_target(raw_target: &str) -> SignTarget

Resolves raw CLI input into a concrete target type.

Checks the filesystem first. If no file exists at the path, assumes a Git reference.

Args:

• raw_target - The raw string input from the CLI.

Usage:

let target = parse_sign_target("HEAD");
assert!(matches!(target, SignTarget::CommitRange(_)));