Function split_batch_xy 

pub fn split_batch_xy(
    batch: &RecordBatch,
    target: &str,
    cols_to_drop: &[String],
) -> Result<(ChunkTable, Vec<f32>, ColGraph), String>

Extract feature table X, target Y, and column metadata (materializes owned columns).

Prefer split_batch_views internally for zero-copy numeric ingest.