Setzt eine globale CSS-Regel für alle Scrollbars innerhalb des POS-Interfaces
(`.pos *::-webkit-scrollbar`) auf 8px Breite und Höhe. Dadurch erhalten alle
scrollbaren Elemente eine konsistente und bedienfreundliche Scrollbar-Darstellung,
insbesondere für Touchscreen- und Terminal-Geräte.
When adding a new order via the customer sidebar, the ProductScreen
was not explicitly activated. As a result, the screen_data context
expected by pos_time_based_products was missing, and no play button
was shown for time-based products.
This patch explicitly calls `this.pos.showScreen("ProductScreen")`
after creating a new order to restore compatibility with third-party
POS components that rely on the current screen state.
