优化声音关闭的逻辑

local_plugins/agent_service/ios/agent_service/Sources/agent_service/AgentServiceImpl.swift

@@ -1707,14 +1707,16 @@ class ChatApiStreamCallback: StreamCallback {
                 return
             }
             
+            if (responseBuilder.isEmpty) { //关闭声音
+                 try agentService.audioPlayer?.stopAwaitSound()
+            }
+
             responseBuilder += token
-            
             if speakResponse && reply && broadcast{
                 try agentService.azureTtsHelper?.speakStream(sessionid:sessionid,token)
                 // 在开始流式TTS时立即停止气泡音
             }
             if (reply && token != "") {
-                try agentService.audioPlayer?.stopAwaitSound()
                 try agentService.sendEvent(name: "assistant_token", data: ["sessionid":sessionid,"token": token])
             }
         }catch {