home: use xdg.configFile where appropriate

users/simon/modules/htop.nix

@@ -1,6 +1,6 @@
 {
-  home.file = {
-    ".config/htop/htoprc".text = ''
+  xdg.configFile = {
+    "htop/htoprc".text = ''
       color_scheme=6
     '';
   };

users/simon/modules/sway.nix

@@ -215,9 +215,9 @@ in
       export _JAVA_AWT_WM_NONREPARENTING=1
     '';
   };
-  home.file = {
+  xdg.configFile = {
     # home-manager’s waybar module performs additional checks that are overly strict
-    ".config/waybar/config".text = builtins.toJSON {
+    "waybar/config".text = builtins.toJSON {
       layer = "top";
       position = "top";
       height = 24;
@@ -375,9 +375,11 @@ in
         tooltip-format = "<big>{:%Y %B}</big>\n<tt><small>{calendar}</small></tt>";
       };
     };
-    ".config/waybar/style.css".source = pkgs.substituteAll ({
+    "waybar/style.css".source = pkgs.substituteAll ({
       src = ../files/waybar/style.css;
     } // solarized);
+  };
+  home.file = {
     ".zprofile".text = ''
       if [[ -z $WAYLAND_DISPLAY ]] && [[ $(tty) = /dev/tty1 ]] && command -v sway >/dev/null ; then
           systemctl --user start graphical-session.target