Function resolve_stable_path 

pub fn resolve_stable_path(
    binary: &Path,
    policy: ScoringPolicy,
) -> Result<Candidate, Error>

Resolve the single best candidate for binary under policy.

Convenience composition of find_candidates + rank_candidates: returns the top-ranked candidate. Because find_candidates is non-empty on success, this always returns a tagged candidate when it returns Ok (never a fabricated tagless one).