Enable vim system-wide

This is required so it can be the default editor for all users that
don’t set another editor.

modules/default.nix

@@ -84,7 +84,10 @@
       ];
 
       programs.nano.enable = false;
-      programs.vim.defaultEditor = true;
+      programs.vim = {
+        enable = true;
+        defaultEditor = true;
+      };
 
       # Clean temporary files on boot
       boot.tmp.cleanOnBoot = true;