feat(justfile): switch away from nh

replaces nh with a super cool and awesome bash script that basically
does the exact same thing except i am the one who wrote it so it's
cooler true and real

switch.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+bold=$(tput bold)
+reset=$(tput sgr0)
+
+flake="$1"
+
+echo "${bold}Building configuration...$reset"
+configuration=$(sudo nixos-rebuild dry-activate --flake "$flake" --keep-going "${@:2}")
+echo "$configuration"
+
+nix run "$flake#nixosConfigurations.$(hostname).pkgs.nvd" -- diff /run/current-system "$configuration"
+
+read -n1 -rp "${bold}Activate new configuration? [y/N]$reset " answer
+echo
+
+if [[ $answer =~ ^[Yy]$ ]]; then
+  sudo "$configuration/bin/switch-to-configuration" switch
+else
+  echo "${bold}Not activating :($reset"
+  exit 1
+fi