refactor config with better structure

nixos/hardware/nvidia.nix

@@ -0,0 +1,24 @@
+{ pkgs, ... }:
+
+{
+  services.xserver.videoDrivers = [ "nvidia" ];
+
+  hardware.nvidia = {
+    branch = "bleeding_edge";
+    modesetting.enable = true;
+    open = true;
+    nvidiaSettings = true;
+  };
+
+  environment.systemPackages = with pkgs; [
+    egl-wayland
+    lact
+    libva-utils
+    nvidia-vaapi-driver
+    nvtopPackages.nvidia
+  ];
+
+  # LACT GPU control daemon
+  systemd.packages = with pkgs; [ lact ];
+  systemd.services.lactd.wantedBy = [ "multi-user.target" ];
+}