feat(search): focus and highlight found message in chat

- store focused message id per chat
- scroll to target message and highlight it after search selection
- clear focus automatically after short timeout

web/src/pages/ChatsPage.tsx

@@ -17,6 +17,7 @@ export function ChatsPage() {
   const activeChatId = useChatStore((s) => s.activeChatId);
   const chats = useChatStore((s) => s.chats);
   const setActiveChatId = useChatStore((s) => s.setActiveChatId);
+  const setFocusedMessage = useChatStore((s) => s.setFocusedMessage);
   const loadMessages = useChatStore((s) => s.loadMessages);
   const activeChat = chats.find((chat) => chat.id === activeChatId);
   const isReadOnlyChannel = Boolean(activeChat && activeChat.type === "channel" && activeChat.my_role === "member");
@@ -147,6 +148,7 @@ export function ChatsPage() {
                   key={`search-msg-${message.id}`}
                   onClick={() => {
                     setActiveChatId(message.chat_id);
+                    setFocusedMessage(message.chat_id, message.id);
                     setSearchOpen(false);
                   }}
                 >