refactor(messaging): replace WebSocket with SSE for real-time message handling

Replace WebSocket-based real-time communication with Server-Sent Events (SSE) across the messaging infrastructure. This includes:

- Create new SSEClient datasource to manage SSE connections
- Create new SSEMessageHandler to process SSE events
- Update ProcessMessageUseCase to use SSEClient instead of WebSocketClient
- Update MessageManager and MessageStateManager to work with SSE handlers
- Rename connection state variables from `isWebSocketConnected` to `isSSEConnected`
- Update type definitions in dto.ts (WSEventType → SSEEventType, etc.)
- Delete obsolete WebSocketClient and WebSocketMessageHandler files
- Update comments and documentation to reflect SSE terminology

This refactoring aligns with the backend's SSE implementation for better compatibility with React Native's networking capabilities.

src/stores/messageManager.ts

@@ -8,7 +8,7 @@
  * 
  * 架构特点：
  * - 管理conversations和messages状态
- * - 统一处理WebSocket消息
+ * - 统一处理SSE消息
  * - 统一处理本地数据库读写
  * - 提供订阅机制供React组件使用
  */
@@ -83,7 +83,7 @@ interface MessageManagerState {
   systemUnreadCount: number;
 
   // 连接状态
-  isWebSocketConnected: boolean;
+  isSSEConnected: boolean;
 
   // 当前活动会话ID（用户正在查看的会话）
   currentConversationId: string | null;
@@ -131,7 +131,7 @@ interface ReadStateRecord {
 
 class MessageManager {
   private state: MessageManagerState;
-  private wsUnsubscribe: (() => void) | null = null;
+  private sseUnsubscribe: (() => void) | null = null;
   private currentUserId: string | null = null;
   private authUnsubscribe: (() => void) | null = null;
   private lastReconnectSyncAt: number = 0;
@@ -158,7 +158,7 @@ class MessageManager {
       messagesMap: new Map(),
       totalUnreadCount: 0,
       systemUnreadCount: 0,
-      isWebSocketConnected: false,
+      isSSEConnected: false,
       currentConversationId: null,
       isLoadingConversations: false,
       loadingMessagesSet: new Set(),
@@ -281,8 +281,8 @@ class MessageManager {
           return;
         }
 
-        // 2. 初始化WebSocket监听
-        this.initWebSocketListeners();
+        // 2. 初始化SSE监听
+        this.initSSEListeners();
 
         // 3. 加载会话列表
         await this.fetchConversations();
@@ -320,9 +320,9 @@ class MessageManager {
   }
 
   destroy(): void {
-    if (this.wsUnsubscribe) {
-      this.wsUnsubscribe();
-      this.wsUnsubscribe = null;
+    if (this.sseUnsubscribe) {
+      this.sseUnsubscribe();
+      this.sseUnsubscribe = null;
     }
     this.state.subscribers.clear();
     this.state.isInitialized = false;
@@ -330,11 +330,11 @@ class MessageManager {
     this.activatingConversationTasks.clear();
   }
 
-  // ==================== WebSocket 处理 ====================
+  // ==================== SSE 处理 ====================
 
-  private initWebSocketListeners(): void {
-    if (this.wsUnsubscribe) {
-      this.wsUnsubscribe();
+  private initSSEListeners(): void {
+    if (this.sseUnsubscribe) {
+      this.sseUnsubscribe();
     }
 
 
@@ -380,7 +380,7 @@ class MessageManager {
 
     // 监听连接状态
     sseService.onConnect(() => {
-      this.state.isWebSocketConnected = true;
+      this.state.isSSEConnected = true;
       this.notifySubscribers({
         type: 'connection_changed',
         payload: { connected: true },
@@ -403,7 +403,7 @@ class MessageManager {
     });
 
     sseService.onDisconnect(() => {
-      this.state.isWebSocketConnected = false;
+      this.state.isSSEConnected = false;
       this.notifySubscribers({
         type: 'connection_changed',
         payload: { connected: false },
@@ -585,7 +585,7 @@ class MessageManager {
   }
 
   /**
-   * 处理新消息（WebSocket推送）
+   * 处理新消息（SSE推送）
    * 这是核心方法，必须立即处理并同步到所有订阅者
    */
   private async handleNewMessage(message: (WSChatMessage | WSGroupChatMessage) & { _isAck?: boolean }): Promise<void> {
@@ -2014,10 +2014,10 @@ class MessageManager {
   }
 
   /**
-   * 获取WebSocket连接状态
+   * 获取SSE连接状态
    */
   isConnected(): boolean {
-    return this.state.isWebSocketConnected;
+    return this.state.isSSEConnected;
   }
 
   /**
@@ -2122,7 +2122,7 @@ class MessageManager {
 
     subscriber({
       type: 'connection_changed',
-      payload: { connected: this.state.isWebSocketConnected },
+      payload: { connected: this.state.isSSEConnected },
       timestamp: Date.now(),
     });