如何使用PhpSpreadsheet合并行输出Excel表格以展示客户和产品信息？

$data = [
    "customer" => "西卡若卡",
    "product" => [
        [
            "name" => "瓶-500ml塑料瓶",
            "parts" => "24牙35克",
            "rongliang" => "500ml"
        ],
        [
            "name" => "内塞-500ml塑料瓶",
            "parts" => "19小孔内塞+盖板",
        ],
        [
            "name" => "盖子-500ml塑料瓶",
            "parts" => "24牙双层pp盖",
        ],
    ]
];

use PhpOffice\PhpSpreadsheet\Spreadsheet;
use PhpOffice\PhpSpreadsheet\Writer\Xlsx;

$spreadsheet = new Spreadsheet();
$sheet = $spreadsheet->getActiveSheet();

// 写入客户信息
$sheet->setCellValue('A1', '客户');
$sheet->setCellValue('B1', $data['customer']);

// 写入产品信息并处理单元格合并
$row = 2;
foreach ($data['product'] as $product) {
    $sheet->setCellValue('A' . $row, '产品名称');
    $sheet->setCellValue('B' . $row, $product['name']);
    $sheet->setCellValue('C' . $row, '部件');
    $sheet->setCellValue('D' . $row, $product['parts']);

    if (isset($product['rongliang'])) {
        $sheet->setCellValue('E' . $row, '容量');
        $sheet->setCellValue('F' . $row, $product['rongliang']);
    } else {
        // 合并E列和F列的单元格
        $sheet->mergeCells('E' . $row . ':F' . $row);
    }

    $row++;
}

// 保存Excel文件
$writer = new Xlsx($spreadsheet);
$writer->save('customer_product_info.xlsx');