Add VirtualBox support with disabled default

hosts/Garand-Desktop/system-modules.nix

@@ -3,6 +3,7 @@ _: {
   Container & Packaging
   */
   docker.enable = true; # Docker: container runtime and management
+  virtualbox.enable = false; # VirtualBox: PC emulator
   flatpak = {
     enable = true; # Flatpak: universal packaging system for Linux
     packages = {

hosts/Garand-Laptop/system-modules.nix

@@ -3,6 +3,7 @@ _: {
   Container & Packaging
   */
   docker.enable = true; # Docker: container runtime and management
+  virtualbox.enable = false; # VirtualBox: PC emulator
   flatpak = {
     enable = true; # Flatpak: universal packaging system for Linux
     packages = {

hosts/default/system-modules.nix

@@ -3,6 +3,7 @@ _: {
   Container & Packaging
   */
   docker.enable = true; # Docker: container runtime and management
+  virtualbox.enable = false; # VirtualBox: PC emulator
   flatpak = {
     enable = true; # Flatpak: universal packaging system for Linux
     packages = {

modules/core/default.nix

@@ -22,6 +22,7 @@
     ./tailscale.nix
     ./thunar.nix
     ./user.nix
+    ./virtualbox.nix
     ./xdg.nix
     ./xserver.nix
     inputs.stylix.nixosModules.stylix

modules/core/virtualbox.nix

@@ -0,0 +1,17 @@
+{
+  pkgs,
+  lib,
+  config,
+  ...
+}: {
+  options.virtualbox.enable = lib.mkEnableOption "Enable VirtualBox";
+
+  config.virtualisation.virtualbox.host = lib.mkIf config.virtualbox.enable {
+    enable = true;
+    package = pkgs.virtualbox;
+    enableKvm = true;
+    enableHardening = true;
+    enableExtensionPack = false;
+    addNetworkInterface = false;
+  };
+}