// نمونه سرور بک‌اند (Node.js + Express)
app.post('/api/download', async (req, res) => {
  const { shareString } = req.body;
  const response = await fetch('https://rubika.ir/api/v6/getPostData', {
    method: 'POST',
    body: JSON.stringify({
      api_version: '6',
      method: 'getPostData',
      data: { share_string: shareString }
    })
  });
  const data = await response.json();
  res.json(data);
});