nixos: add nh and use it's gc

nixos.nix

@@ -24,11 +24,15 @@
     "flakes"
   ];
 
-  # Enable automatic garbage collection.
-  nix.gc = {
-    automatic = true;
-    dates = "weekly";
-    options = "--delete-older-than 1w";
+  # Enable nh, a bundle of CLI utilities for NixOS
+  programs.nh = {
+    enable = true;
+
+    # Enable automatic garbage collection.
+    clean.enable = true;
+    clean.extraArgs = "--keep-since 4d --keep 3";
+
+    flake = "/home/wizardlink/.system";
   };
 
   # Optimize storage

switch

@@ -1,12 +0,0 @@
-#!/etc/profiles/per-user/wizardlink/bin/fish
-
-function build
-  sudo nixos-rebuild switch --flake ~/.system\#nixos $argv[1]
-end
-
-if test "--fast" = "$argv[1]"
-  build --fast
-else
-  build
-end
-