refactor(sunshine.nix): update display manager and X server configuration

hosts/architect/sunshine.nix

@@ -95,6 +95,7 @@ in
         origin_web_ui_allowed = "lan";
         min_threads = 12;
         log_path = "sunshine.log";
+        back_button_timeout = 2500;
       };
       applications = {
         env = {
@@ -133,22 +134,24 @@ in
       };
     };
 
-    xserver = {
-      enable = true;
-      videoDrivers = [ "nvidia" ];
-      desktopManager.gnome.enable = true;
     displayManager = {
-        gdm = {
-          enable = true;
-          autoSuspend = false;
       autoLogin = {
         inherit user;
         enable = true;
       };
+
+      sddm = {
+        enable = true;
+        wayland.enable = false;
+
       };
-        defaultSession = "gnome-xorg";
     };
 
+    xserver = {
+      enable = true;
+      videoDrivers = [ "nvidia" ];
+      desktopManager.xfce.enable = true;
+
       monitorSection = ''
         HorizSync       5.0 - 1000.0
         VertRefresh     5.0 - 1000.0