Add an option to configure the expiration time for downloadable PDF links. Currently, the links users receive are valid for 48 hours, but there needs to be an option to set custom expiration times, such as 2 hours or 4 hours, to enhance access control for private content. This feature should allow admins to choose from a range of expiration times, manually revoke access, or set default values. Implementing this would improve security and provide greater flexibility with stricter access controls.
