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/db/seed_credentials.sql

@@ -17,9 +17,9 @@ VALUES
   ('model_003', 'SiliconFlow-Qwen3-Embedding-4B',  'Qwen/Qwen3-Embedding-4B',        'Embedding', 'openai',    'https://api.siliconflow.cn/v1',                           'sk-uudpgflahqqjbofhgcbwjjefgwhvwwmxgeyehcueqlemwavq',     '',          1.0, '',   TRUE),
   ('model_004', 'SiliconFlow-CosyVoice2-0.5B',     'FunAudioLLM/CosyVoice2-0.5B',    'TTS',       'openai',    'https://api.siliconflow.cn/v1',                           'sk-uudpgflahqqjbofhgcbwjjefgwhvwwmxgeyehcueqlemwavq',     'FunAudioLLM/CosyVoice2-0.5B:anna',    1.0, '',   FALSE),
   ('model_005', 'Qwen-Max',                        'qwen-max',                       'LLM',       'openai',    'https://dashscope.aliyuncs.com/compatible-mode/v1',        'sk-qwen-4d8e2a6f0c',                                     '',          1.0, '',   FALSE),
-  ('model_006', '讯飞语音识别',                     'iat',                            'ASR',       'xfyun',     'https://iat-api.xfyun.cn/v2/iat',                          'xf-asr-9b1c3d5e7a',                                      '',          1.0, 'zh', TRUE),
+  ('model_006', '讯飞语音识别',                     'iat',                            'ASR',       'xfyun',     'https://iat-api.xfyun.cn/v2/iat',                          '{"appId":"replace-me","apiKey":"replace-me","apiSecret":"replace-me"}', '',          1.0, 'zh', TRUE),
   ('model_007', 'Paraformer 识别',                 'paraformer-realtime-v2',         'ASR',       'dashscope', 'https://dashscope.aliyuncs.com/api/v1/services/audio/asr', 'sk-paraformer-2e4f6a',                                    '',          1.0, 'zh', FALSE),
-  ('model_008', '讯飞语音合成',                     'tts',                            'TTS',       'xfyun',     'https://tts-api.xfyun.cn/v2/tts',                          'xf-tts-6c8a0b2d4f',                                      'xiaoyan',    1.0, '',   TRUE),
+  ('model_008', '讯飞语音合成',                     'tts',                            'TTS',       'xfyun',     'https://tts-api.xfyun.cn/v2/tts',                          '{"appId":"replace-me","apiKey":"replace-me","apiSecret":"replace-me"}', 'xiaoyan',    1.0, '',   TRUE),
   ('model_009', 'CosyVoice 合成',                  'cosyvoice-v1',                   'TTS',       'dashscope', 'https://dashscope.aliyuncs.com/api/v1/services/audio/tts', 'sk-cosyvoice-1a3c5e',                                     'longxiaochun', 1.0, '', FALSE),
   ('model_010', 'GPT Realtime',                    'gpt-4o-realtime-preview',        'Realtime',  'openai',    'https://api.openai.com/v1/realtime',                       'sk-realtime-3b5d7f9a1c',                                 '',          1.0, '',   TRUE),
   ('model_011', 'Gemini Live',                     'gemini-2.0-flash-live',          'Realtime',  'gemini',    'https://generativelanguage.googleapis.com/v1beta',         'gm-live-5e7a9c1b3d',                                     '',          1.0, '',   FALSE),