refactor(asr): 重构speech_to_text方法以接收artifacts参数

移除各ASR提供者中重复的get_current_artifacts调用，改为通过参数传递artifacts
修改base类中process_audio方法，根据combined_pcm_data长度决定是否创建artifacts
更新所有speech_to_text方法签名，添加artifacts可选参数并更新文档字符串

main/xiaozhi-server/core/providers/asr/doubao.py

@@ -232,12 +232,11 @@ class ASRProvider(ASRProviderBase):
             yield data[offset:data_len], True
 
     async def speech_to_text(
-        self, opus_data: List[bytes], session_id: str, audio_format="opus"
+        self, opus_data: List[bytes], session_id: str, audio_format="opus", artifacts=None
     ) -> Tuple[Optional[str], Optional[str]]:
         """将语音数据转换为文本"""
 
         try:
-            artifacts = self.get_current_artifacts()
             if artifacts is None:
                 return "", None