Add support for Nobara

Like Zorin, they ship the browser themselves. I didn't look into how (whether they add our repo, or if our package is in their repos), but we should make sure the script works on that distro and doesn't mess anything up.

Start with the install.sh script and trace how it identifies distributions and handles browser repositories or packages. Compare the existing Zorin support with Nobara's setup, then verify that running the script on Nobara completes without unintended repository or package changes.

Written by the indexing model from the issue text.