add wallpapers to assets, fix nh cleaning job, reenable stylix

modules/hosts/takamaki/takamaki.nix

@@ -50,7 +50,10 @@
         cli = {
           fastfetch.enable = true;
           color-converter.enable = true;
-          nh.enable = true;
+          nh = {
+            enable = true;
+            clean.enable = true;
+          };
         };
 
         gui = {