feat(config): configure umbriel package and ignore runtime theme files

.chezmoidata/packages.yaml

@@ -130,6 +130,11 @@ packages:
         - voxtype-bin
         - xdg-terminal-exec
         - hyprland-preview-share-picker
+      # [cachyos] repo; installed only when that repo is configured. Umbriel
+      # has no usable AUR package (`umbriel` is a placeholder, `umbriel-git`
+      # conflicts with the repo build), so elsewhere it is installed by hand.
+      cachyos:
+        - umbriel
   darwin:
     brew:
       - fish