nixos/ibus: fix missing dconf profile

Fix ibus user preferences not being saved. ibus-daemon was falling back on null configuration due to missing "ibus" dconf profile.

nixos/modules/i18n/input-method/ibus.nix

@@ -64,6 +64,8 @@ in
     # Without dconf enabled it is impossible to use IBus
     programs.dconf.enable = true;
 
+    programs.dconf.profiles.ibus = "${ibusPackage}/etc/dconf/profile/ibus";
+
     services.dbus.packages = [
       ibusAutostart
     ];