Fix API compatibility and add user/role/permission and asset import/export

backend_new/app/db/base.py

@@ -0,0 +1,12 @@
+"""
+数据库基类和配置
+"""
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import DeclarativeBase
+
+class Base(DeclarativeBase):
+    """数据库模型基类"""
+    pass
+
+
+__all__ = ["Base"]