Fix: Promptbar initializes in open state for Mobile (#542)

* Fix for DEFAULT_SYSTEM_PROMPT

* Set the prompt bar to be hidden if screen < 640

pages/api/home/home.tsx

@@ -275,6 +275,7 @@ const Home = ({
 
     if (window.innerWidth < 640) {
       dispatch({ field: 'showChatbar', value: false });
+      dispatch({ field: 'showPromptbar', value: false });
     }
 
     const showChatbar = localStorage.getItem('showChatbar');