all application options will adapt to environment

when used either with nixos (no home-manager) or home-manager standalone, `features.applications.<name>.enable` options still perform some functionality, rather than assuming a full nixos + home-manager setup like before

modules/features/applications/gui/remmina.nix

@@ -1,4 +1,23 @@
 { inputs, self, ... }: {
+  flake.nixosModules.graphics = { pkgs, config, lib, ... }: {
+    options.features.applications.gui.remmina.enable = lib.mkEnableOption "remmina";
+    
+    config = let
+      mkIfElse = with lib; p: yes: no:
+        mkMerge [
+          (mkIf p yes)
+          (mkIf (!p) no)
+        ];
+    in lib.mkIf (config.features.applications.gui.remmina.enable) (mkIfElse (config.features.nixos.home-manager.enable) {
+      home-manager.users.grey.features.applications.gui.remmina.enable = lib.mkDefault true;
+    } {
+      environment.systemPackages = with pkgs; [
+        remmina
+        freerdp
+      ];
+    });
+  };
+
   flake.homeModules.graphics = { pkgs, config, lib, ... }: {
     options.features.applications.gui.remmina.enable = lib.mkEnableOption "remmina";