Rework profile/env for shells

I dug at this for a while and it never worked well. There might be some
way to do this with what currently exists, but it isn't obvious if so
and I don't think it is worth it. I think I may prefer to just set brave
to dark mode and keep the frame minimal. Also, my plan is to switch to
using qutebrowser as my primary browser anyway.

src_files/.config/zz-this-box/themes/mars/neovim.lua

@@ -1,3 +0,0 @@
-return {
-    colorscheme_name = 'mars'
-}

src_files/.config/zz-this-box/themes/mars/tmux.conf

@@ -1,2 +0,0 @@
-set-window-option -g window-style bg=default # transparency
-set-option -g status-style 'bg=default fg=#e07b5f'