feat: add stylix theme

Break Changes:
- May need reconfigure fcitx5 input method

system/modules/plymouth.nix

@@ -3,11 +3,6 @@
   boot = {
     plymouth = {
       enable = true;
-      theme = "hexagon_dots";
-      themePackages = with pkgs; [
-        (adi1090x-plymouth-themes.override { selected_themes = [ "hexagon_dots" ]; })
-        (catppuccin-plymouth.override { variant = "frappe"; })
-      ];
     };
 
     consoleLogLevel = 0;