Enhance pipeline execution and voice preview handling for graceful call termination

- Introduce mechanisms in the pipeline to ensure that the end call process waits for the completion of the end speech before hanging up, improving user experience during call termination.
- Update the useVoicePreview hook to handle server-initiated call endings gracefully, distinguishing between normal and error disconnections.
- Adjust TTS stop frame timeout settings to optimize the timing of call terminations, ensuring timely responses without unnecessary delays.
- Refactor related components to support the new end call logic, enhancing overall workflow management and user interaction.

backend/services/pipecat/service_factory.py

@@ -21,6 +21,11 @@ from services.pipecat.xfyun_super_tts import (
 )
 from services.pipecat.xfyun_tts import DEFAULT_XFYUN_TTS_URL, XfyunTTSService
 
+# TTS「说完」判定的空闲时长:默认 3.0s 过长(导致工作流结束节点说完后还要等约 3s
+# 才挂断,也拖慢日常轮次的交还)。设 1.0s 既能让结束语文字/音频送达,又更跟手。
+# 流式 TTS 句间音频间隔通常远小于 1s,不会把一段多句回复误判为结束。
+TTS_STOP_FRAME_TIMEOUT_S = 1.0
+
 
 def _language(value: str) -> Language | None:
     if not value:
@@ -107,6 +112,7 @@ def create_tts(cfg: AssistantConfig):
             volume=int(cfg.tts_values.get("volume") or 50),
             pitch=int(cfg.tts_values.get("pitch") or 50),
             push_stop_frames=True,
+            stop_frame_timeout_s=TTS_STOP_FRAME_TIMEOUT_S,
         )
     if cfg.tts_interface_type not in {"openai-tts", "dashscope-tts"}:
         raise ValueError(f"不支持的 TTS 接口类型: {cfg.tts_interface_type}")
@@ -117,6 +123,7 @@ def create_tts(cfg: AssistantConfig):
     return OpenAITTSService(
         api_key=cfg.tts_api_key or config.TTS_API_KEY,
         base_url=cfg.tts_base_url or config.TTS_BASE_URL,
+        stop_frame_timeout_s=TTS_STOP_FRAME_TIMEOUT_S,
         settings=OpenAITTSService.Settings(
             model=cfg.tts_model or config.TTS_MODEL,
             voice=voice,