Drop support for i3

While I first switched to EXWM warily and thinking it would only be temporary,
it seems like this switch is here to stay. It turns out that EXWM was exactly
the integration I've been looking for. How serendipitous it that I found it when
I did.

Thank you, @tazjin.

configs/shared/aliases.zsh

@@ -221,7 +221,6 @@ alias ea='e ~/aliases.zsh'
 alias ef='e ~/functions.zsh'
 alias el='e ~/variables.zsh'
 alias ex='e ~/.Xresources'
-alias ei='e ~/.config/i3/config'
 alias em='e ~/.tmux.conf'
 # TODO: consider DRYing this up with `e`. Unfortunately, `sudo` won't support
 # aliases.
@@ -234,7 +233,6 @@ alias sa='source ~/aliases.zsh'
 alias sf='source ~/functions.zsh'
 alias sl='source ~/variables.zsh'
 alias sx='xrdb ~/.Xresources'
-alias si='i3-msg restart'
 alias sm='tmux source-file ~/.tmux.conf'
 alias sn='sudo nixos-rebuild switch'