Move system/home/default.nix into system/default.nix,
system/home/desktop/default.nix into system/desktop.nix to reduce
unnecessary duplication. Moved everything in home/desktop up to home/
and adjusted paths accordingly. Moved wallpapers up to system/ since
it makes sense with where it's used.
Merge allowUnfreePredicate into single place again since it seems to
override rather than combine if used multiple times.
Install NoMachine on all machines again by default.
Add stylix with theme, font and image configuration.
Change all relevant (current) options to that nix evaluates without
error, not fully tested yet though.
Remove plasma manager and associated components.
Condensed some files - remove some standalone files for packages with
much smaller configuration now that they're not being manually themed.
Add zathura with some initial config, colour scheme is currently
incomplete but placeholder comments in place for required keys.
Don't autostart twinkle on work machines, some issue with detected
ALSA source/sink.