Add support for Xfyun ASR and TTS services in the backend

- Introduce new Xfyun ASR and TTS services, enabling integration with iFlytek's voice recognition and synthesis capabilities.
- Update AssistantConfig model to include interface types for STT and TTS.
- Enhance credential testing to validate Xfyun credentials.
- Modify service factory to create Xfyun services based on configuration.
- Update README with new configuration details for Xfyun integration.
- Add new frontend components for visualizing audio streams and managing user interactions.

backend/services/credential_tester.py

@@ -9,6 +9,7 @@ import wave
 import httpx
 
 from schemas import CredentialTestRequest, CredentialTestResult
+from services.pipecat.xfyun_config import parse_xfyun_credential
 
 TEST_TIMEOUT_SECONDS = 10.0
 
@@ -123,3 +124,25 @@ async def test_openai_credential(
             message="无法连接到模型服务",
             detail=str(exc)[:300],
         )
+
+
+def test_xfyun_credential(config: CredentialTestRequest) -> CredentialTestResult:
+    """Validate the Xfyun credential packed into the existing api_key field.
+
+    Actual signed-WebSocket synthesis/recognition is exercised by the voice
+    pipeline; this check deliberately avoids consuming provider quota.
+    """
+    try:
+        parse_xfyun_credential(config.api_key)
+    except ValueError as exc:
+        return CredentialTestResult(
+            ok=False,
+            message="讯飞凭证格式无效",
+            detail=str(exc),
+        )
+
+    return CredentialTestResult(
+        ok=True,
+        message="讯飞凭证格式有效",
+        detail="请在语音测试页验证签名、识别和合成链路",
+    )