Function remote_lookup 

pub fn remote_lookup(
    cache: &CacheDir,
    cache_key: &str,
    cli_label: &str,
) -> Option<CacheEntry>

Look up a cache key in the remote GHA cache.

On hit, downloads the tar blob and unpacks it into the local cache via CacheDir::store. Returns the local CacheEntry on success. Returns None on remote miss. Logs warnings on errors and returns None (non-fatal).

cli_label prefixes diagnostic output (e.g. "ktstr" or "cargo ktstr").