Function remote_pin_replace_named 

pub async fn remote_pin_replace_named(
    kubo_url: &str,
    service: &str,
    name: &str,
    cid: &str,
    overwrite: bool,
) -> Result<bool>

Pin cid on the remote service and schedule best-effort replacement of stale pins with this name.

With overwrite the fresh pin is added under the requested name before the background worker removes stale CIDs with that exact name. Returns whether cleanup was scheduled.