Add support for AppImage

[armr-dev]

I'd like to suggest adding AppImage support to the application. Currently, Linux support is limited to .deb packages, which restricts compatibility to Debian-based distributions.

My proposal is to add an additional step to the Deploy action that automatically generates an AppImage alongside the existing .deb file. This would expand Linux compatibility to a wider range of distributions.

I'm willing to implement this feature and submit a pull request. Before investing the effort, I'd appreciate the maintainers' feedback on whether this aligns with the project's goals.

[Qronikarz]

Already suggested before, but no word from the dev yet:
#2948