Enhance voice configuration with idle prompt features and new TTS settings

- Added idle prompt timeout, maximum count, and text to multiple voice configuration files to improve user interaction during idle periods.
- Updated greeting mode to 'fastgpt_opener' in relevant configurations for a more dynamic greeting experience.
- Introduced a new voice configuration file for xfyun TTS, including detailed service settings and parameters.
- Refactored the pipeline to handle idle prompts and user turn events, ensuring smoother interaction flow.
- Adjusted the VAD and turn configurations to accommodate new idle prompt features.

config/voice.json

@@ -42,7 +42,10 @@
       "没有",
       "否"
     ],
-    "user_speech_timeout_sec": 0.8
+    "user_speech_timeout_sec": 0.8,
+    "idle_prompt_timeout_sec": 3.0,
+    "idle_prompt_max_count": 3,
+    "idle_prompt_text": "你好，请问还在吗？"
   },
   "agent": {
     "system_prompt": "You are a helpful, friendly voice assistant. Keep responses concise and natural for spoken conversation.",