feat(api): use Tencent ASR flash with 16k_zh_large and dev transcript logs

Replace CreateRecTask polling with recording-file flash API, add TENCENT_APP_ID,
remove server-side pydub slicing, and log ASR recognition text at INFO in development.

Co-authored-by: Cursor <cursoragent@cursor.com>

api/app/core/config.py

@@ -42,6 +42,7 @@ class Settings(BaseSettings):
 
     tencent_secret_id: str = ""
     tencent_secret_key: str = ""
+    tencent_app_id: str = ""
 
     wechat_pay_api_v3_key: str = ""
     wechat_pay_private_key: str = ""