wluma: add systemd user service

nixos/configuration.nix

@@ -121,8 +121,7 @@
     gnumake
     cifs-utils
     tailscale
-  #  vim # Do not forget to add an editor to edit configuration.nix! The Nano editor is also installed by default.
-  #  wget
+    wluma
   ];
 
   # set global environment variables
@@ -174,6 +173,19 @@
     extraUpFlags = [ "--ssh" ];
   };
 
+  # enable wluma for automatic brightness adjustment
+  systemd.user.services.wluma = {
+    enable = true;
+    description = "Adjusting screen brightness based on screen contents and amount of ambient light";
+    after = [ "graphical-session.target" ];
+    partOf = [ "graphical-session.target" ];
+    serviceConfig = {
+      ExecStart = "${pkgs.wluma}/bin/wluma";
+      Restart = "always";
+    };
+    wantedBy = [ "graphical-session.target" ];
+  };
+
   # Enable the OpenSSH daemon.
   # services.openssh.enable = true;