refactor(message): replace SubscriptionManager with Zustand selectors

Remove custom SubscriptionManager class and adopt Zustand's built-in
selector mechanism for reactive state updates. This simplifies the
architecture by eliminating manual subscription management and relying
on Zustand's automatic dependency tracking for component re-renders.

Key changes:
- Remove SubscriptionManager class from store.ts
- Replace all notifySubscribers calls with direct store updates
- Update hooks to use Zustand selectors with useShallow for complex data
- Remove subscribe/unsubscribe patterns from MessageManager
- Simplify EmbeddedChat to use selector instead of local state
- Rename requestConversationListRefresh to refreshConversations

src/stores/message/services/MessageSendService.ts

@@ -2,14 +2,16 @@
  * 消息发送服务
  * 处理消息发送相关逻辑
  * 
- * 重构说明：直接使用 zustand store 替代 IMessageStateManager
+ * 重构说明：
+ * - 直接使用 zustand store 替代 IMessageStateManager
+ * - 移除了 SubscriptionManager 调用，Zustand 的 set() 会自动触发组件重渲染
  */
 
 import type { MessageResponse, MessageSegment, ConversationResponse } from '../../../types/dto';
 import { messageService } from '../../../services/messageService';
 import { saveMessage } from '../../../services/database';
 import type { IMessageSendService } from '../types';
-import { useMessageStore, subscriptionManager, mergeMessagesById } from '../store';
+import { useMessageStore, mergeMessagesById } from '../store';
 
 export class MessageSendService implements IMessageSendService {
   private getCurrentUserId: () => string | null;
@@ -53,28 +55,9 @@ export class MessageSendService implements IMessageSendService {
         const updatedMessages = mergeMessagesById(existingMessages, [newMessage]);
         store.setMessages(conversationId, updatedMessages);
 
-        // 关键：立即广播消息列表更新
-        subscriptionManager.notifySubscribers({
-          type: 'messages_updated',
-          payload: {
-            conversationId,
-            messages: updatedMessages,
-            newMessage,
-            source: 'send',
-          },
-          timestamp: Date.now(),
-        });
-
         // 更新会话最后消息
         this.updateConversationWithNewMessage(conversationId, newMessage);
 
-        // 通知消息已发送
-        subscriptionManager.notifySubscribers({
-          type: 'message_sent',
-          payload: { conversationId, message: newMessage },
-          timestamp: Date.now(),
-        });
-
         // 保存到本地数据库
         const textContent = segments
           ?.filter((s: any) => s.type === 'text')
@@ -100,11 +83,6 @@ export class MessageSendService implements IMessageSendService {
       return null;
     } catch (error) {
       console.error('[MessageSendService] 发送消息失败:', error);
-      subscriptionManager.notifySubscribers({
-        type: 'error',
-        payload: { error, context: 'sendMessage' },
-        timestamp: Date.now(),
-      });
       return null;
     }
   }