v0.29.5 — parent_row provenance for blended row-transform functions
Client.table_in_out_function gains parent_row_callback, decoding vgi_rpc.parent_row#b64
provenance for a blended (RowTransformFunction) worker's 1->N/1->0 emits — the
mechanism vgi-polars's row_transform_function bridge needs. Backward-compatible:
off unless a caller passes the new callback.
See vgi/protocol.py's _decode_parent_rows and Client.table_in_out_function's docstring.