Function finalize_oci_image 

pub fn finalize_oci_image<ObjectID: FsVerityHashValue>(
    repo: &Arc<Repository<ObjectID>>,
    manifest_json: &[u8],
    config_json: &[u8],
    layer_refs: &[(OciDigest, ObjectID)],
    name: Option<&str>,
) -> Result<FinalizeResult<ObjectID>>

Finalize an OCI image whose layers are already imported into repo.

Given the raw manifest and config JSON (exact bytes, so their sha256 digests are preserved) and the ordered (diff_id, layer_verity) pairs, this writes the config and manifest splitstreams, generates the composefs EROFS image, and optionally tags the manifest under name. Idempotent.

Returns ((manifest_digest, manifest_verity), (config_digest, config_verity)).