Function encode_batch 

pub fn encode_batch(batch: &RecordBatch) -> Result<Vec<u8>, IpcError>

Encode a RecordBatch as Arrow IPC stream bytes.

Output: schema header + one record batch + end-of-stream marker — suitable for one-shot transmission across a wasm boundary.

Errors

Returns IpcError::Arrow if the writer cannot serialize the batch (e.g., schema-incompatible types).