feat(desktop): add tumbler support for thunar thumbnails

modules/nixos/desktop/thunar.nix

@@ -2,7 +2,10 @@
   flake.modules.nixos.desktop =
     { pkgs, ... }:
     {
-      services.gvfs.enable = true;
+      services = {
+        gvfs.enable = true;
+        tumbler.enable = true;
+      };
 
       programs.thunar = {
         enable = true;