Function commit_author_login 

pub fn commit_author_login(
    owner: &str,
    repo: &str,
    email: &str,
    sha: &str,
    token: Option<&str>,
) -> Option<String>

Resolve a commit author’s GitHub login from a representative commit SHA via GET /repos/{owner}/{repo}/commits/{sha} → .author.login.

Best-effort by design: any failure (no gh, no auth, offline, unknown SHA, commit email not linked to a GitHub account) returns None with at most a debug-level trace — callers fall back to name-based rendering and must never fail a release pipeline over a missing login.

Results (including failures) are memoized process-wide per (owner, repo, email), so each unique author email costs one API call per run regardless of how many commits or crates reference it.