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/core/usecases/ProcessMessageUseCase.ts

@@ -1,11 +1,11 @@
 /**
  * ProcessMessageUseCase - 处理消息用例
- * 处理消息的业务逻辑，协调 Repository 和 WebSocketClient
+ * 处理消息的业务逻辑，协调 Repository 和 SSEClient
  * 纯业务逻辑，无UI依赖
  */
 
 import { messageRepository } from '../../data/repositories/MessageRepository';
-import { webSocketClient, WebSocketEventType } from '../../data/datasources/WebSocketClient';
+import { sseClient, SSEEventType } from '../../data/datasources/SSEClient';
 import {
   Message,
   Conversation,
@@ -62,7 +62,7 @@ class ProcessMessageUseCase {
    */
   initialize(currentUserId: string | null): void {
     this.currentUserId = currentUserId;
-    this.setupWebSocketListeners();
+    this.setupSSEListeners();
   }
 
   /**
@@ -79,51 +79,51 @@ class ProcessMessageUseCase {
   }
 
   /**
-   * 设置WebSocket监听器
+   * 设置SSE监听器
    */
-  private setupWebSocketListeners(): void {
+  private setupSSEListeners(): void {
     // 监听私聊消息
-    const unsubChat = webSocketClient.on('chat', (message) => {
+    const unsubChat = sseClient.on('chat', (message) => {
       this.handleNewMessage(message);
     });
 
     // 监听群聊消息
-    const unsubGroupMessage = webSocketClient.on('group_message', (message) => {
+    const unsubGroupMessage = sseClient.on('group_message', (message) => {
       this.handleNewMessage(message);
     });
 
     // 监听私聊已读回执
-    const unsubRead = webSocketClient.on('read', (message) => {
+    const unsubRead = sseClient.on('read', (message) => {
       this.handleReadReceipt(message);
     });
 
     // 监听群聊已读回执
-    const unsubGroupRead = webSocketClient.on('group_read', (message) => {
+    const unsubGroupRead = sseClient.on('group_read', (message) => {
       this.handleGroupReadReceipt(message);
     });
 
     // 监听私聊消息撤回
-    const unsubRecall = webSocketClient.on('recall', (message) => {
+    const unsubRecall = sseClient.on('recall', (message) => {
       this.handleRecallMessage(message);
     });
 
     // 监听群聊消息撤回
-    const unsubGroupRecall = webSocketClient.on('group_recall', (message) => {
+    const unsubGroupRecall = sseClient.on('group_recall', (message) => {
       this.handleGroupRecallMessage(message);
     });
 
     // 监听群聊输入状态
-    const unsubGroupTyping = webSocketClient.on('group_typing', (message) => {
+    const unsubGroupTyping = sseClient.on('group_typing', (message) => {
       this.handleGroupTyping(message);
     });
 
     // 监听群通知
-    const unsubGroupNotice = webSocketClient.on('group_notice', (message) => {
+    const unsubGroupNotice = sseClient.on('group_notice', (message) => {
       this.handleGroupNotice(message);
     });
 
     // 监听连接状态
-    const unsubConnected = webSocketClient.on('connected', () => {
+    const unsubConnected = sseClient.on('connected', () => {
       this.notifySubscribers({
         type: 'connection_changed',
         payload: { connected: true },
@@ -131,7 +131,7 @@ class ProcessMessageUseCase {
       });
     });
 
-    const unsubDisconnected = webSocketClient.on('disconnected', () => {
+    const unsubDisconnected = sseClient.on('disconnected', () => {
       this.notifySubscribers({
         type: 'connection_changed',
         payload: { connected: false },
@@ -397,7 +397,7 @@ class ProcessMessageUseCase {
       groupId: groupIdStr,
       data: data || {},
       timestamp: timestamp || Date.now(),
-      messageId,
+      messageId: message_id,
       seq,
     };