feat(nixos): add support for plymouth (#166)

Co-authored-by: seth <getchoo@tuta.io>

modules/nixos/plymouth.nix

@@ -0,0 +1,22 @@
+{ config
+, pkgs
+, lib
+, ...
+}:
+let
+  inherit (lib) ctp mkIf;
+  cfg = config.boot.plymouth.catppuccin;
+  enable = cfg.enable && config.boot.plymouth.enable;
+in
+{
+  options.boot.plymouth.catppuccin = ctp.mkCatppuccinOpt "plymouth";
+
+  config.boot.plymouth = mkIf enable {
+    theme = "catppuccin-${cfg.flavour}";
+    themePackages = [
+      (pkgs.catppuccin-plymouth.override {
+        variant = cfg.flavour;
+      })
+    ];
+  };
+}

test.nix

@@ -29,7 +29,10 @@ testers.runNixOSTest {
       common
     ];
 
-    boot.loader.grub = enable;
+    boot = {
+      loader.grub = enable;
+      plymouth = enable;
+    };
 
     services = {
       displayManager.sddm = enable;