Enable VirtualBox and add C# Omnisharp support

Update ChatGPT desktop entry icon SHA256 to match new asset.

hosts/Garand-Laptop/system-modules.nix

@@ -3,7 +3,7 @@ _: {
   Container & Packaging
   */
   docker.enable = true; # Docker: container runtime and management
-  virtualbox.enable = false; # VirtualBox: PC emulator
+  virtualbox.enable = true; # VirtualBox: PC emulator
   virualization.enable = false; # GUI application for managing local and remote virtual machines through libvirt
   flatpak = {
     enable = true; # Flatpak: universal packaging system for Linux

modules/home/xdg/desktop-entries.nix

@@ -46,7 +46,7 @@
       displayName = "ChatGPT";
       url = "https://chatgpt.com/";
       iconUrl = "https://static.vecteezy.com/system/resources/previews/031/110/149/large_2x/chatgpt-logo-transparent-free-png.png";
-      iconSha = "sha256-WXR/d28ynaBe+kZpnkUAaHcriDVSge98weS5Dza+AvQ=";
+      iconSha = "sha256-ZWmhchblQkksW02eduVrkUSPAlWPGC2fjqxrAGAF5jw=";
     }
     {
       name = "claude";

modules/home/zed/extensions.nix

@@ -21,5 +21,6 @@ _: {
     "opencode"
     "fish"
     "tera"
+    "csharp"
   ];
 }

modules/home/zed/extra-packages.nix

@@ -11,5 +11,6 @@
     deputy
     tailwindcss-language-server
     typescript-language-server
+    omnisharp-roslyn
   ];
 }

modules/home/zed/user-settings/lsp.nix

@@ -153,5 +153,9 @@
         };
       };
     };
+    omnisharp.binary = {
+      path = lib.getExe pkgs.omnisharp-roslyn;
+      arguments = ["-lsp"];
+    };
   };
 }