fix(web-core): stabilize unread sync and realtime dedup behavior

- make prependMessage return insertion status for dedup-safe unread increments

- increment unread only on newly inserted incoming messages

- trigger chat list refresh on websocket reconnect to resync unread counters

web/src/hooks/useRealtime.ts

@@ -42,6 +42,7 @@ export function useRealtime() {
 
       ws.onopen = () => {
         reconnectAttemptsRef.current = 0;
+        void useChatStore.getState().loadChats();
       };
 
       ws.onmessage = (messageEvent) => {
@@ -60,17 +61,18 @@ export function useRealtime() {
           if (!Number.isFinite(chatId) || !message?.id) {
             return;
           }
+          let wasInserted = false;
           if (clientMessageId && message.sender_id === authStore.me?.id) {
             chatStore.confirmMessageByClientId(chatId, clientMessageId, message);
           } else {
-            chatStore.prependMessage(chatId, message);
+            wasInserted = chatStore.prependMessage(chatId, message);
           }
           if (message.sender_id !== authStore.me?.id) {
             ws.send(JSON.stringify({ event: "message_delivered", payload: { chat_id: chatId, message_id: message.id } }));
             if (chatId === chatStore.activeChatId) {
               ws.send(JSON.stringify({ event: "message_read", payload: { chat_id: chatId, message_id: message.id } }));
               chatStore.clearUnread(chatId);
-            } else {
+            } else if (wasInserted) {
               chatStore.incrementUnread(chatId);
             }
           }