Function restore_named_batches 

pub fn restore_named_batches(
    save_dir: &Path,
    names: &[&str],
) -> Result<Vec<(String, Vec<RecordBatch>)>>

Restore named RecordBatch collections from a save directory.

Returns a vector of (name, batches) for each name found on disk. Missing files are silently skipped (returns empty vec for first-run case).