feat: system settings stored as applets in virtual folder

scripts/copy_icons.sh

@@ -51,6 +51,7 @@ ICONS=(
     "apps/scalable/utilities-terminal.svg"
     "apps/scalable/system-file-manager.svg"
     "apps/scalable/preferences-desktop-apps.svg"
+    "categories/scalable/preferences-system.svg"
     "apps/scalable/accessories-calculator.svg"
     "apps/scalable/web-browser.svg"
     "places/scalable/folder.svg"