feat: 重构接口日志页面与接口监控看板，支持HTTP方法过滤和实时轮询

backend/app/config.py

@@ -15,6 +15,9 @@ class Settings(BaseSettings):
     tz: str = "Asia/Shanghai"
     # consecutive failures before upstream goes unhealthy
     unhealthy_threshold: int = 3
+    # external API log retention
+    external_api_log_retention_days: int = 30
+    external_api_log_slow_ms: int = 3000
 
     @property
     def cors_origin_list(self) -> list[str]: