Enable VirtualBox and add C# Omnisharp support

Update ChatGPT desktop entry icon SHA256 to match new asset.

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

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