feat: Implement user-tenant relationship management with CRUD operations and access control

backend/api/v1/modules/a76/tenants/models.py

@@ -3,11 +3,15 @@ Modelos ORM para gestión de tenants
 """
 from sqlalchemy import Column, Integer, String, DateTime, Boolean, Text, Enum as SQLEnum
 from sqlalchemy.sql import func
-from sqlalchemy.orm import Mapped, mapped_column
+from sqlalchemy.orm import Mapped, mapped_column, relationship
 from datetime import datetime
+from typing import List, TYPE_CHECKING
 from core.database import Base
 import enum
 
+if TYPE_CHECKING:
+    from api.v1.modules.a76.user_tenant.models import UserTenant
+
 
 class TenantType(enum.Enum):
     """Tipo de tenant según tamaño y necesidades"""
@@ -49,5 +53,8 @@ class Tenant(Base):
     updated_at: Mapped[datetime] = mapped_column(DateTime, nullable=False, default=func.now(), onupdate=func.now())
     deleted_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
     
+    # Relación con UserTenant
+    user_relations: Mapped[List["UserTenant"]] = relationship("UserTenant", back_populates="tenant")
+    
     def __repr__(self):
         return f"<Tenant(id={self.id}, name={self.name}, type={self.type.value})>"