Add a link to a BitTorrent web client

[josecelano]

If you use the Brave browser, you can click on the magnet link, and you can start downloading the torrent without installing a BitTorrent client

I think for this feature to work, the tracker should provide webtorrent support.

For users not using Brave we could add an extra link to other BitTorrent web clients:

• https://btorrent.xyz/
• https://github.com/pldubouilh/webtorrent-webui
• https://haven.pages.dev/torrent-client/public/
• https://github.com/drakonkat/crawfish/blob/main/README.md

Or maybe we could implement a webtorrent client inside the Index GUI, so that users can just click and start downloading.

I haven't read deeply about Webtorrent, so this could not be feasible or hard to implement.

cc @da2ce7