enable rtkit and scheduler

i enable rtkit and scx_lavd for more performance or something, it seems
to work pretty decently

tundra/programs.nix

···
   ...
 }:
 {
+  security.rtkit.enable = true;
   programs = {
     zsh.enable = true;
     niri = {
···
     };
   };
   services = {
+    scx = {
+      enable = true;
+      scheduler = "scx_lavd";
+      extraArgs = [ "--performance" ];
+    };
     pipewire = {
       enable = true;
       alsa.enable = true;