sprint1: entity_permissions table + owned_mixin + universal permission service + API + migrations 0049+0050

app/models/contact.py

@@ -27,9 +27,10 @@ from sqlalchemy.dialects.postgresql import UUID as PGUUID
 from sqlalchemy.orm import Mapped, mapped_column, relationship
 
 from app.core.db import Base, TenantMixin
+from app.models.owned_mixin import OwnedMixin
 
 
-class Contact(Base, TenantMixin):
+class Contact(Base, TenantMixin, OwnedMixin):
     """Unified contact entity — can be a company or a person.
 
     type='company': name is the company name, firstname/surname empty.