Bug Title: Download pauses when Brave is in background (Android)

When downloading any file (e.g., movies), the download only continues if the Brave browser’s Downloads page stays open. As soon as the user switches tabs, opens a new page, or minimizes the app, the download pauses automatically.

Tested on: Android 15, Multiple smartphones, Latest Brave mobile version

Expected: Downloads should continue in the background.

Actual: Downloads stop until the user reopens the Brave Downloads page.