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/models.py

@@ -31,6 +31,9 @@ class AssistantConfig(BaseModel):
     stt_language: str = ""
     tts_speed: float = 1.0
     realtimeModel: str = ""
+    realtime_interface_type: str = ""
+    realtime_values: dict = {}
+    realtime_secrets: dict = {}
     llm_interface_type: str = "openai-llm"
     stt_interface_type: str = "openai-asr"
     tts_interface_type: str = "openai-tts"
@@ -51,6 +54,8 @@ class AssistantConfig(BaseModel):
     stt_base_url: str = ""
     tts_api_key: str = ""
     tts_base_url: str = ""
+    realtime_api_key: str = ""
+    realtime_base_url: str = ""
 
 
 class SignalingOffer(BaseModel):