feat(chat): add promotional external entry flow

src/stores/chat/chat-context.tsx

@@ -11,6 +11,7 @@ import { useMachine } from "@xstate/react";
 
 import { chatMachine } from "./chat-machine";
 import type { ChatEvent, ChatState as MachineContext } from "./chat-machine";
+import { appendPromotionMessage } from "./chat-promotion";
 
 /**
  * 对外暴露的 State 形状
@@ -20,6 +21,8 @@ import type { ChatEvent, ChatState as MachineContext } from "./chat-machine";
  */
 interface ChatState {
   messages: MachineContext["messages"];
+  historyMessages: MachineContext["messages"];
+  promotion: MachineContext["promotion"];
   isReplyingAI: boolean;
   upgradePromptVisible: boolean;
   upgradeReason: MachineContext["upgradeReason"];
@@ -51,7 +54,12 @@ export function ChatProvider({ children }: ChatProviderProps) {
   // 映射 XState 状态机快照 → 原 ChatState 形状
   const chatState = useMemo<ChatState>(
     () => ({
-      messages: state.context.messages,
+      messages: appendPromotionMessage(
+        state.context.messages,
+        state.context.promotion,
+      ),
+      historyMessages: state.context.messages,
+      promotion: state.context.promotion,
       isReplyingAI: state.context.isReplyingAI,
       upgradePromptVisible: state.context.upgradePromptVisible,
       upgradeReason: state.context.upgradeReason,