Function detect_cwd_atomgit_repo 

pub fn detect_cwd_atomgit_repo(cwd: &Path) -> Result<Option<RepoRef>>

Detect the atomgit.com (owner, repo) of a local git checkout by running git remote get-url origin in cwd. Returns:

• Ok(Some(RepoRef)) — found an atomgit.com origin.
• Ok(None) — not a git repo, or origin points elsewhere / missing. Callers treat this as “can’t validate, proceed with a warning”.
• Err(...) — the git command itself failed unexpectedly.