refactor: 优化前端网络层

- 优化ApiService，移除冗余代码
- 优化WebSocketClient连接处理

app-android/app/src/main/java/com/huaga/life_echo/network/ApiService.kt

@@ -98,21 +98,6 @@ class ApiService(
         }
     }
     
-    suspend fun organizeConversation(conversationId: String): Result<Unit> {
-        return try {
-            val response = client.post("$BASE_URL/api/conversations/$conversationId/organize") {
-                contentType(ContentType.Application.Json)
-            }
-            if (response.status.isSuccess()) {
-                Result.success(Unit)
-            } else {
-                Result.failure(Exception("整理失败: ${response.status}"))
-            }
-        } catch (e: Exception) {
-            Result.failure(e)
-        }
-    }
-    
     // ==================== 回忆录相关API ====================
     
     suspend fun getBookInfo(): Result<BookDto> {

app-android/app/src/main/java/com/huaga/life_echo/network/WebSocketClient.kt

@@ -3,9 +3,7 @@ package com.huaga.life_echo.network
 import io.ktor.client.*
 import io.ktor.client.engine.okhttp.*
 import io.ktor.client.plugins.websocket.*
-import io.ktor.client.plugins.contentnegotiation.*
 import io.ktor.client.plugins.logging.*
-import io.ktor.serialization.kotlinx.json.*
 import io.ktor.websocket.*
 import io.ktor.http.*
 import kotlinx.coroutines.flow.*
@@ -20,12 +18,8 @@ import android.util.Log
 class WebSocketClient {
     private val client = HttpClient(OkHttp) {
         install(WebSockets)
-        install(ContentNegotiation) {
-            json(Json {
-                ignoreUnknownKeys = true
-                encodeDefaults = false
-            })
-        }
+        // 注意：WebSocket不需要ContentNegotiation插件，因为消息是手动序列化的
+        // ContentNegotiation插件会导致尝试序列化WebSocket会话对象，引发序列化错误
         install(Logging) {
             level = LogLevel.INFO
         }