M0: implement operational core

Backend: SQLAlchemy models, Alembic migrations, requirements lockfile. Frontend: pinned deps, package-lock, vite-env types fix. Verified compose build/health, pytest, ruff clean.

backend/app/models/vehicle.py

@@ -0,0 +1,23 @@
+from sqlalchemy import Boolean, Integer, String
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.db import Base
+from app.models.mixins import TimestampMixin, UUIDPrimaryKeyMixin
+
+OPERATIONAL_STATUSES = ("available", "rented", "cleaning", "maintenance", "blocked")
+
+
+class Vehicle(UUIDPrimaryKeyMixin, TimestampMixin, Base):
+    __tablename__ = "vehicles"
+
+    public_ref: Mapped[str] = mapped_column(String(20), unique=True, nullable=False)
+    make: Mapped[str] = mapped_column(String(80), nullable=False)
+    model: Mapped[str] = mapped_column(String(80), nullable=False)
+    model_year: Mapped[int] = mapped_column(Integer, nullable=False)
+    registration_number: Mapped[str] = mapped_column(String(40), unique=True, nullable=False)
+    location: Mapped[str] = mapped_column(String(120), nullable=False)
+    operational_status: Mapped[str] = mapped_column(String(20), nullable=False)
+    odometer_km: Mapped[int] = mapped_column(Integer, nullable=False)
+    next_service_km: Mapped[int] = mapped_column(Integer, nullable=False)
+    active: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True)
+    version: Mapped[int] = mapped_column(Integer, nullable=False, default=1)