M34: enforce domain integrity in PostgreSQL

backend/app/models/vehicle.py

@@ -1,4 +1,4 @@
-from sqlalchemy import Boolean, Integer, String
+from sqlalchemy import Boolean, CheckConstraint, Integer, String
 from sqlalchemy.orm import Mapped, mapped_column
 
 from app.core.db import Base
@@ -9,6 +9,16 @@ OPERATIONAL_STATUSES = ("available", "rented", "cleaning", "maintenance", "block
 
 class Vehicle(UUIDPrimaryKeyMixin, TimestampMixin, Base):
     __tablename__ = "vehicles"
+    __table_args__ = (
+        CheckConstraint(
+            "operational_status IN ('available','rented','cleaning','maintenance','blocked')",
+            name="ck_vehicles_operational_status",
+        ),
+        CheckConstraint("model_year BETWEEN 1900 AND 2100", name="ck_vehicles_model_year"),
+        CheckConstraint("odometer_km >= 0", name="ck_vehicles_odometer"),
+        CheckConstraint("next_service_km >= 0", name="ck_vehicles_next_service"),
+        CheckConstraint("version >= 1", name="ck_vehicles_version"),
+    )
 
     public_ref: Mapped[str] = mapped_column(String(20), unique=True, nullable=False)
     make: Mapped[str] = mapped_column(String(80), nullable=False)