automatic overlay for ./packages directory

also gamescope added system-wide and in flatpak for steam

global-default.nix

@@ -1,15 +1,22 @@
 {
+  lib,
   config,
   pkgs,
   specialArgs,
   ...
 }: let
-modules-dir = ./modules;
+packageFileNames = builtins.attrNames (builtins.readDir ./packages);
+packageNames = map (x: lib.removeSuffix ".nix" x) packageFileNames;
+packagesOverlay = (final: prev: lib.genAttrs packageNames (name: (prev.pkgs.callPackage ./packages/${name}.nix { })));
 in {
   imports = [
     ./hosts/${specialArgs.hostname}/hardware-configuration.nix
-    "${modules-dir}/nh.nix"
-    "${modules-dir}/home-manager.nix"
+    ./modules/nh.nix
+    ./modules/home-manager.nix
+  ];
+
+  nixpkgs.overlays = [
+    packagesOverlay
   ];
 
   networking.hostName = specialArgs.hostname;