feat: implement pivot-currency model, rbac smart tokens & fix circular imports

backend/app/models/document.py

@@ -2,7 +2,8 @@ from sqlalchemy import Column, String, Integer, Boolean, DateTime, ForeignKey
 from sqlalchemy.dialects.postgresql import UUID
 from sqlalchemy.sql import func
 import uuid
-from app.db.base import Base
+# JAVÍTVA: Közvetlenül a base_class-ból importálunk, nem a base-ből!
+from app.db.base_class import Base
 
 class Document(Base):
     __tablename__ = "documents"