How it works:
1. Each row's first column is the SKU / identifier.
2. Every other cell is scanned for URLs (including comma-separated ones).
3. Files download into /files/{column-name}/
4. File types are detected via Content-Disposition headers, magic bytes, and MIME types.
5. Output CSV replaces URLs with https://csv-tool.dolcedev.com/files/… paths.
6. Use Clean Up Server when done to delete all downloaded files.