Replace lightdm with greetd

modules/gui.nix

@@ -9,16 +9,14 @@ with pkgs;
 
 {
   # Display manager
-  services.xserver.enable = true;
-  services.xserver.displayManager = {
-    defaultSession = "sway";
-    autoLogin = {
-      enable = true;
-      user = "coolneng";
-    };
-    lightdm = {
-      enable = true;
-      greeter.enable = false;
+  services.greetd = {
+    enable = true;
+    settings = rec {
+      initial_session = {
+        command = "${sway}/bin/sway";
+        user = "coolneng";
+      };
+      default_session = initial_session;
     };
   };