How can I configure the first row of my Excel document as a header row?
I can only find ways to customize the style of the cells in the first row. For this I made myself a little helper method, but there must be a flag I can set, right?
What I'm currently using as a "workaround":
/**
 * Applies the header style (bold font, and gray bg) to the given row in a sheet.
 * 
 * @param Worksheet $sheet
 * @param int $row
 * 
 * @return Worksheet
 */
private function applyHeaderStyle(Worksheet $sheet, int $row = 1): Worksheet
{
    $highestColumn = $sheet->getHighestColumn();
    $sheet
        ->getStyle("A{$row}:{$highestColumn}{$row}")
        ->getFont()
        ->setBold(true);
    $sheet
        ->getStyle("A{$row}:{$highestColumn}{$row}")
        ->getFill()
        ->setFillType(Fill::FILL_SOLID)
        ->getStartColor()
        ->setARGB('FFBEC0BF');
    return $sheet;
}
But this will apply only styles and only to a limited set of cells and not the infinite length of the row.
Update:
Getting the style like ->getStyle("{$row}:{$row}") and applying a bold font and background color to it, like proposed in this answer, works for the font style but not for the background color.
Apart from that, I still wonder if an Excel header is really "only" marked by its design, or if there is a flag for it.