Restrict upload permissions

[ZeroClover]

I regret to see that Firefox Send had to be temporarily closed because it was abused to distribute malware.

On-premise "Send" instances may also be subject to such threats, and these "Send" instances cannot track malware uploaders by logging into Firefox accounts.

Besides, there is currently no way to prevent others from uploading files by merely restricting access to the directory (such as Basic Auth).

Perhaps a simple site password should be implemented to prevent unauthorized visitors from uploading files, but anyone with a download link can still download files shared by the site owner.