Add first-class AppImage install support (omarchy install appimage)

[Paulie420]

Omarchy has no dedicated path for installing a standalone .AppImage. Today it means doing the desktop-integration steps by hand: move the file somewhere stable, chmod +x, run --appimage-extract to pull the icon out, copy the icon into ~/.local/share/icons/hicolor//apps/, and hand-write a .desktop file into ~/.local/share/applications/ — reverse-engineering the exec name and icon name from the AppImage's bundled .desktop file along the way.

This is exactly the kind of "optional software install" flow omarchy install app already handles for packaged apps — it'd be great to have an equivalent for local AppImages, e.g.:

omarchy install appimage [display-name]
which would:

• move/symlink the AppImage into a standard location (e.g. ~/.local/bin/)
• extract and install the icon into the user's icon theme dir
• generate a valid .desktop entry (pulling Name/Icon/Categories from the AppImage's own bundled .desktop when present, falling back to sane defaults)
• optionally register it for omarchy uninstall / removal later

Happy to test against a couple of real-world AppImages if that's useful.

[bmaltais]

I have created a plugin to handle that. It is in here: https://github.com/bmaltais/StartAppImage

I will submit it to the marketplace later today.