fix(chat): queue outgoing messages

src/stores/chat/chat-state.ts

@@ -3,6 +3,7 @@ import type { UiMessage } from "@/data/dto/chat";
 export interface ChatState {
   messages: UiMessage[];
   isReplyingAI: boolean;
+  pendingReplyCount: number;
   /**
    * WebSocket 连接状态（仅 VIP 用户会话期间 true）
    * - VIP true：走 WS
@@ -34,6 +35,7 @@ export interface ChatState {
 export const initialState: ChatState = {
   messages: [],
   isReplyingAI: false,
+  pendingReplyCount: 0,
   wsConnected: false,
   upgradePromptVisible: false,
   upgradeReason: null,