Extend nvidia role to include driver configuration

The nvidia role now handles full driver configuration instead of just
packages. Added options for open driver, modesetting, power management,
graphics settings, and driver package selection.

Updated zix790prors and wixos machine configs to use the new role
options, removing duplicated hardware.nvidia configuration blocks.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

machines/wixos/configuration.nix

@@ -17,6 +17,15 @@
       enable = true;
       wayland = true;
     };
+    nvidia = {
+      enable = true;
+      package = "latest";
+      graphics.extraPackages = with pkgs; [
+        mesa
+        libvdpau-va-gl
+        libva-vdpau-driver
+      ];
+    };
     users.enable = true;
   };
 
@@ -29,28 +38,13 @@
   wsl.wslConf.network.hostname = "wixos";
   wsl.wslConf.user.default = "johno";
 
-  services.xserver.videoDrivers = [ "nvidia" ];
-  hardware.graphics = { 
-    enable = true;
-
-    extraPackages = with pkgs; [
-      mesa
-      libvdpau-va-gl
-      libva-vdpau-driver
-    ];
-  };
+  # WSL-specific environment variables for graphics
   environment.sessionVariables = {
     LD_LIBRARY_PATH = [
       "/usr/lib/wsl/lib"
       "/run/opengl-driver/lib"
     ];
   };
-  hardware.nvidia = {
-    modesetting.enable = true;
-    nvidiaSettings = true;
-    open = true;
-    package = config.boot.kernelPackages.nvidiaPackages.latest;
-  };
 
   # This value determines the NixOS release from which the default
   # settings for stateful data, like file locations and database versions