chore: baseline plantilla-proyectos como base del CRM

backend/api/v1/common/base_models.py

@@ -0,0 +1,33 @@
+from datetime import datetime
+
+from sqlalchemy import DateTime, ForeignKey, Integer
+from sqlalchemy.orm import Mapped, mapped_column
+from sqlalchemy.sql import func
+
+
+class BaseTimestampMixin:
+    """Mixin for basic timestamp fields (no soft delete)"""
+
+    created_at: Mapped[datetime] = mapped_column(
+        DateTime, nullable=False, server_default=func.now()
+    )
+    updated_at: Mapped[datetime] = mapped_column(
+        DateTime, nullable=False, server_default=func.now(), onupdate=func.now()
+    )
+
+
+class TimestampMixin(BaseTimestampMixin):
+    """Mixin for common timestamp fields including soft delete"""
+
+    deleted_at: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
+
+
+class TenantScopedMixin:
+    """Mixin para entidades multi-tenant.
+
+    company_id no tiene FK declarada aquí — agrégala en cada modelo
+    apuntando a la tabla de compañías de tu proyecto.
+    """
+
+    tenant_id: Mapped[int] = mapped_column(Integer, ForeignKey("core.tenants.id"), nullable=False, index=True)
+    company_id: Mapped[int] = mapped_column(Integer, nullable=False, index=True)