feat: add QR code login and enhance chat experience

- Add QR code login flow with scanner and confirmation screens
- Implement swipe-to-reply in chat with SwipeableMessageBubble
- Replace FlatList with FlashList for chat performance optimization
- Add Schedule stack navigator with CourseDetail screen support
- Configure deep linking for QR code login (carrotbbs://qrcode/login/:sessionId)
- Update branding from 胡萝卜 to 萝卜社区
- Display dynamic app version in settings

src/screens/message/components/ChatScreen/useChatScreen.ts

@@ -390,6 +390,16 @@ export const useChatScreen = () => {
       return;
     }
 
+    // 禁用自动滚动到底部，防止加载历史消息后滚动位置跳转
+    shouldAutoScrollOnEnterRef.current = false;
+    // 清除所有待执行的自动滚动定时器
+    autoScrollTimersRef.current.forEach(clearTimeout);
+    autoScrollTimersRef.current = [];
+
+    // 保存加载前的滚动位置和内容高度
+    const scrollYBefore = scrollPositionRef.current.scrollY;
+    const contentHeightBefore = scrollPositionRef.current.contentHeight;
+
     setLoadingMore(true);
 
     try {
@@ -400,6 +410,23 @@ export const useChatScreen = () => {
         const minSeq = Math.min(...messages.map(m => m.seq));
         setFirstSeq(minSeq);
       }
+
+      // 加载完成后，恢复滚动位置
+      // 使用 setTimeout 确保 FlashList 已经更新
+      setTimeout(() => {
+        if (flatListRef.current) {
+          // 计算新的滚动位置，保持相对位置不变
+          const newContentHeight = scrollPositionRef.current.contentHeight;
+          const heightDiff = newContentHeight - contentHeightBefore;
+          const newScrollY = scrollYBefore + heightDiff;
+          
+          // 滚动到计算后的位置
+          flatListRef.current.scrollToOffset({
+            offset: newScrollY,
+            animated: false,
+          });
+        }
+      }, 100);
     } catch (error) {
       console.error('加载历史消息失败:', error);
     } finally {
@@ -409,13 +436,19 @@ export const useChatScreen = () => {
 
   // 列表内容尺寸变化后触发首次自动滚动
   const handleMessageListContentSizeChange = useCallback((contentWidth: number, contentHeight: number) => {
+    // 如果是加载更多历史消息，不要自动滚动
+    if (loadingMore) {
+      return;
+    }
+    
     if (!shouldAutoScrollOnEnterRef.current) return;
-    if (loading || loadingMore) return;
+    if (loading) return;
     if (messages.length === 0) return;
 
     const prevContentHeight = scrollPositionRef.current.contentHeight;
     scrollPositionRef.current.contentHeight = contentHeight;
 
+    // 如果内容高度增加（加载了更多消息），不要自动滚动到底部
     if (prevContentHeight > 0 && contentHeight > prevContentHeight) {
       return;
     }