slab: move config to explicit config block

hosts/slab/configuration.nix

@@ -6,6 +6,17 @@
 { config, lib, pkgs, vars, ... }:
 
 {
+  imports =
+    [ # Include the results of the hardware scan.
+      ./hardware-configuration.nix
+
+      ../../system # nixfiles modules
+      ./nvidia-optimus.nix
+      ./supergfxd.nix
+    ];
+
+
+  config = {
     # nix.settings.experimental-features = ["nix-command" "flakes" ];
 
     fileSystems = lib.mkMerge [
@@ -30,15 +41,6 @@
       }))
     ];
 
-  imports =
-    [ # Include the results of the hardware scan.
-      ./hardware-configuration.nix
-
-      ../../system # nixfiles modules
-      ./nvidia-optimus.nix
-      ./supergfxd.nix
-    ];
-
     # specialisation.plasma.configuration = {
     #   system.nixos.tags = [ "Plasma" ];
     #   nixfiles = {
@@ -312,5 +314,6 @@
     # (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
     system.stateVersion = "23.11"; # Did you read the comment?
 
+  };
 }