rowColumns method
Generic row that accepts PosColumn list (full control)
Implementation
void rowColumns(List<PosColumn> columns) {
_bytes.addAll(_generator.row(columns));
// For preview: try to create simple left-right for 2-col case
if (columns.length == 2) {
final left = columns[0].text;
final right = columns[1].text;
_preview.row(left, right);
} else {
// fallback: simply join texts
final joined = columns.map((c) => c.text).join(' | ');
_preview.text(joined);
}
}