修复在聊天很短没有覆盖整个区域时显示回到底部按钮的bug

app/components/chat.tsx

@@ -438,7 +438,7 @@ export function Chat() {
   const [isLoading, setIsLoading] = useState(false);
   const { submitKey, shouldSubmit } = useSubmitHandler();
   const { scrollRef, setAutoScroll, scrollToBottom } = useScrollToBottom();
-  const [hitBottom, setHitBottom] = useState(false);
+  const [hitBottom, setHitBottom] = useState(true);
   const isMobileScreen = useMobileScreen();
   const navigate = useNavigate();