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/README.md

@@ -55,6 +55,18 @@ ai-video-backend/
 | STT  | SenseVoice / FunASR | 本地 OpenAI 兼容转写服务 |
 | TTS  | CosyVoice | 本地 OpenAI 兼容 TTS 服务 |
 
+### 讯飞 ASR / TTS / SuperTTS
+
+讯飞继续复用 `ProviderCredential` 的现有字段，不增加专属列：
+
+- `interface_type`: `xfyun`
+- `api_url`: 讯飞 WebSocket URL（`https://` 会自动转为 `wss://`）
+- `api_key`: `{"appId":"...","apiKey":"...","apiSecret":"..."}`
+- ASR `model_id`: `iat`
+- 普通 TTS `model_id`: `tts`
+- 超拟人 TTS `model_id`: `supertts`（包含 `/private/` 的 URL 也会自动识别）
+- TTS `voice`: 讯飞音色 ID；`speed=1.0` 对应讯飞正常语速 `50`
+
 ## 本地运行(用 uv,Python 3.12)
 
 ```bash
@@ -97,7 +109,7 @@ docker compose --profile remote up -d
 
 ## 待联调 / TODO
 
-- [ ] `pip install` 后跑通,核对 pipecat 版本的服务/transport 构造参数(代码内有注释)
+- [ ] 联调 Pipecat 1.3.0 语音链路与各 OpenAI 兼容服务
 - [ ] 起本地 SenseVoice / CosyVoice 的 OpenAI 兼容服务
 - [ ] `realtime` 模式(目前只 `pipeline` 级联)
 - [x] 前端 `DebugVoicePanel` 接 `/ws/voice`(参考 dograh `useWebSocketRTC.tsx`)