feat(message): implement message search functionality

Add ability to search messages within a specific conversation. This includes:
- New `MessageSearchScreen` for displaying search results.
- `MessageRepository.searchByConversation` to query messages by keyword and conversation ID.
- Integration of search entry points in `GroupInfoScreen` and `PrivateChatInfoScreen`.
- Support for scrolling to a specific message sequence (`scrollToSeq`) when navigating from search results.
- Enhanced `HighlightText` component to support custom highlight styles.

feat(message): implement message search functionality

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

@@ -97,6 +97,7 @@ export const useChatScreen = (props?: ChatScreenProps) => {
     groupId?: string | string[];
     groupName?: string | string[];
     groupAvatar?: string | string[];
+    scrollToSeq?: string | string[];
   }>();
   // 路由参数（动态段 + query）；群 ID 勿用 Number()，避免超过 2^53-1 时精度丢失
   // 嵌入式模式下优先使用 props，否则从路由参数获取
@@ -112,6 +113,7 @@ export const useChatScreen = (props?: ChatScreenProps) => {
       };
     }
     const isGroupFlag = firstRouteParam(rawParams.isGroupChat);
+    const scrollToSeqParam = firstRouteParam(rawParams.scrollToSeq);
     return {
       conversationId: firstRouteParam(rawParams.conversationId) ?? null,
       userId: firstRouteParam(rawParams.userId) ?? null,
@@ -119,6 +121,7 @@ export const useChatScreen = (props?: ChatScreenProps) => {
       groupId: firstRouteParam(rawParams.groupId),
       groupName: firstRouteParam(rawParams.groupName),
       groupAvatar: firstRouteParam(rawParams.groupAvatar),
+      scrollToSeq: scrollToSeqParam ? Number(scrollToSeqParam) : null,
     };
   }, [
     props?.embeddedConversationId,
@@ -131,9 +134,10 @@ export const useChatScreen = (props?: ChatScreenProps) => {
     rawParams.groupId,
     rawParams.groupName,
     rawParams.groupAvatar,
+    rawParams.scrollToSeq,
   ]);
 
-  const { conversationId: routeConversationId, userId: routeUserId, isGroupChat, groupId: routeGroupId, groupName: routeGroupName, groupAvatar: routeGroupAvatar } = routeParams;
+  const { conversationId: routeConversationId, userId: routeUserId, isGroupChat, groupId: routeGroupId, groupName: routeGroupName, groupAvatar: routeGroupAvatar, scrollToSeq: routeScrollToSeq } = routeParams;
 
   // 当前会话ID（可能在新建私聊会话后动态更新）
   const [conversationId, setConversationId] = useState<string | null>(routeConversationId);
@@ -200,6 +204,7 @@ export const useChatScreen = (props?: ChatScreenProps) => {
   const isBrowsingHistoryRef = useRef(false);
   const hasShownMessageListRef = useRef(false);
   const historyLoadingLockUntilRef = useRef(0);
+  const scrollToSeqRef = useRef<number | null>(null);
 
   // 回复消息状态
   const [replyingTo, setReplyingTo] = useState<GroupMessage | null>(null);
@@ -377,6 +382,7 @@ export const useChatScreen = (props?: ChatScreenProps) => {
     isBrowsingHistoryRef.current = false;
     hasShownMessageListRef.current = false;
     historyLoadingLockUntilRef.current = 0;
+    scrollToSeqRef.current = routeScrollToSeq ?? null;
   }, [conversationId]);
 
   useEffect(() => {
@@ -415,7 +421,7 @@ export const useChatScreen = (props?: ChatScreenProps) => {
     return scrollY <= 100;
   }, [scrollPositionRef]);
 
-  // 首屏加载完成后仅锚定一次到最新消息端
+  // 首屏加载完成后仅锚定一次到最新消息端（有 scrollToSeq 时跳过）
   useEffect(() => {
     if (
       loading ||
@@ -427,6 +433,7 @@ export const useChatScreen = (props?: ChatScreenProps) => {
       return;
     }
     hasInitialAnchorDoneRef.current = true;
+    if (scrollToSeqRef.current != null) return; // 由下方 scrollToSeq effect 处理
     const timer = setTimeout(() => {
       scrollToLatest(false, true, 'initial-anchor');
     }, 0);
@@ -606,6 +613,36 @@ export const useChatScreen = (props?: ChatScreenProps) => {
     }
   }, [conversationId, hasMoreHistory, loadingMore, loadMoreMessages, messages]);
 
+  // 从搜索结果跳转：滚动到目标 seq
+  useEffect(() => {
+    const targetSeq = scrollToSeqRef.current;
+    if (targetSeq == null || !hasInitialAnchorDoneRef.current) return;
+    if (loading || loadingMore) return;
+
+    const found = messages.find(m => m.seq === targetSeq);
+    if (found) {
+      scrollToSeqRef.current = null;
+      isBrowsingHistoryRef.current = true;
+      suppressAutoFollowRef.current = true;
+      const ascendingIndex = messages.findIndex(m => m.seq === targetSeq);
+      const displayIndex = messages.length - 1 - ascendingIndex;
+      setTimeout(() => {
+        flatListRef.current?.scrollToIndex({
+          index: displayIndex,
+          animated: false,
+          viewPosition: 0.5,
+        });
+      }, 50);
+      return;
+    }
+
+    if (hasMoreHistory) {
+      loadMoreHistory();
+    } else {
+      scrollToSeqRef.current = null;
+    }
+  }, [loading, loadingMore, messages, hasMoreHistory, loadMoreHistory]);
+
   // 列表内容尺寸变化：仅同步内容高度，锚点补偿由 loadMoreHistory 统一处理
   const handleMessageListContentSizeChange = useCallback((contentWidth: number, contentHeight: number) => {
     scrollPositionRef.current.contentHeight = contentHeight;