Function conduit_media_path 

fn conduit_media_path(
    media_dir: &Path,
    depth: u8,
    length: u8,
    sha256_hex: &str,
) -> PathBuf

Reconstructs the on-disk path of a Conduit content-addressed media file from the lowercase SHA-256 hex digest naming it, matching Conduit’s split_media_path: media_dir joined with the digest’s shard segments.