Implement StepFun Realtime service and enhance AssistantConfig

- Add new fields to AssistantConfig for realtime interface configuration, including types, values, and secrets.
- Introduce StepFunRealtimeService to handle speech-to-speech processing via WebSocket, integrating STT, LLM, and TTS functionalities.
- Refactor pipeline execution to support a new realtime mode, allowing direct text input processing and immediate responses.
- Update model resource testing to include validation for StepFun Realtime connections.
- Enhance service factory to create realtime services based on configuration settings.
- Modify README documentation to reflect new realtime capabilities and usage instructions.

backend/services/pipecat/service_factory.py

@@ -133,3 +133,33 @@ def create_services(cfg: AssistantConfig):
         f"voice={cfg.voice or config.TTS_VOICE}"
     )
     return create_stt(cfg), create_llm(cfg), create_tts(cfg)
+
+
+def create_realtime_service(cfg: AssistantConfig):
+    """Create a speech-to-speech service that owns STT, LLM, and TTS."""
+    if cfg.realtime_interface_type == "stepfun-realtime":
+        from services.pipecat.stepfun_realtime import StepFunRealtimeService
+
+        return StepFunRealtimeService(
+            api_key=cfg.realtime_api_key,
+            model=cfg.realtimeModel,
+            base_url=cfg.realtime_base_url,
+            instructions=cfg.prompt,
+            voice=str(cfg.realtime_values.get("voice") or "linjiajiejie"),
+            input_sample_rate=int(
+                cfg.realtime_values.get("inputSampleRate") or 24000
+            ),
+            output_sample_rate=int(
+                cfg.realtime_values.get("outputSampleRate") or 24000
+            ),
+            prefix_padding_ms=int(
+                cfg.realtime_values.get("prefixPaddingMs") or 500
+            ),
+            silence_duration_ms=int(
+                cfg.realtime_values.get("silenceDurationMs") or 300
+            ),
+            energy_awakeness_threshold=int(
+                cfg.realtime_values.get("energyAwakenessThreshold") or 2500
+            ),
+        )
+    raise ValueError(f"不支持的 Realtime 接口类型: {cfg.realtime_interface_type}")