Function dataset_physical_identity 

pub fn dataset_physical_identity(
    connection: &Connection,
    metadata_schema: &str,
    study: StudyId,
    name: &str,
    major: i32,
    minor: i32,
    patch: i32,
) -> Result<(Uuid, i64), LakeError>

Captures the committed immutable physical identity while the caller retains its writer reservation (or the operator holds an upgrade maintenance window).