refactor: update routes in web.php for clarity and organization

Imported necessary controller classes (Test, UploadController, DownloadController).
Replaced default route closure with explicit controller methods:
/ now routes to UploadController@index method.
/upload now routes to UploadController@upload method.
/download/{params} now routes to DownloadController@download method, with specific parameters.
Added route names for better route referencing and maintenance.

Author: alirezajavadigit