Fix a lot of missing relationship information, plus some upstream CRUDKit changes.

crudkit/core/base.py

@@ -10,7 +10,13 @@ class CRUDMixin:
     updated_at = Column(DateTime, default=func.now(), onupdate=func.now())
 
     def as_dict(self):
-        return {c.name: getattr(self, c.name) for c in self.__table__.columns}
+        # Combine all columns from all inherited tables
+        result = {}
+        for cls in self.__class__.__mro__:
+            if hasattr(cls, "__table__"):
+                for column in cls.__table__.columns:
+                    result[column.name] = getattr(self, column.name)
+        return result
 
 class Version(Base):
     __tablename__ = "versions"