Function compare_stream_ids 

pub fn compare_stream_ids(a: &str, b: &str) -> Ordering

Compare two Redis stream IDs.

Stream IDs are formatted as {timestamp}-{sequence} (e.g., “1234567890123-0”). This function compares them numerically, not lexicographically.

Returns Ordering::Less if a < b, Equal if a == b, Greater if a > b.