chore: shrink size of config

[phorcys420]

The main thing taking space right now is probably KDE, i think we should replace it with GNOME or remove it altogether because probably we don't need a GUI.

if we really need a GUI then probably a lightweight window manager should suffice, maybe we make the GUI optional too.

so, couple ideas:

• Remove KDE/replace KDE with WM (or smaller DE)
• Remove Firefox (~360 MB)
• Remove mbrola/espeak TTS voices (~645 MB) -> lose speech synthesis (KDE accessibility)

For the appliance:

• We can probably drop all-hardware.nix (linux-firmware), but unsure
• Get rid of nix.registry.nixpkgs.flake -> No offline flake on the appliance box, we probs don't care

[bpmct]

having a desktop env is super helpful at conferences bc then it can HDMI out a video (hence VLC, etc) onto a monitor OR be used to demo the interface (e.g. firefox). we did that at OSS summit and it was awesome

So i'd say hidpi support should be considered and desktop envs should be included.

of course this could be a build option and we could publish a -full or -desktop vs -minimal / -headless option