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/data_quality.py

@@ -0,0 +1,35 @@
+import uuid
+from datetime import datetime
+
+from sqlalchemy import DateTime, String
+from sqlalchemy.dialects.postgresql import JSONB, UUID
+from sqlalchemy.orm import Mapped, mapped_column
+
+from app.core.db import Base
+from app.models.mixins import TimestampMixin, UUIDPrimaryKeyMixin
+
+RULE_TYPES = (
+    "possible_duplicate_customer",
+    "missing_required_field",
+    "odometer_regression",
+    "booking_overlap",
+    "vehicle_status_conflict",
+)
+SEVERITIES = ("low", "medium", "high")
+ISSUE_STATUSES = ("open", "deferred", "resolved", "rejected")
+
+
+class DataQualityIssue(UUIDPrimaryKeyMixin, TimestampMixin, Base):
+    __tablename__ = "data_quality_issues"
+
+    public_ref: Mapped[str] = mapped_column(String(20), unique=True, nullable=False)
+    rule_type: Mapped[str] = mapped_column(String(40), nullable=False)
+    entity_type: Mapped[str] = mapped_column(String(30), nullable=False)
+    entity_id: Mapped[uuid.UUID] = mapped_column(UUID(as_uuid=True), nullable=False)
+    severity: Mapped[str] = mapped_column(String(10), nullable=False)
+    status: Mapped[str] = mapped_column(String(20), nullable=False, default="open")
+    evidence_json: Mapped[dict] = mapped_column(JSONB, nullable=False, default=dict)
+    proposed_action_json: Mapped[dict] = mapped_column(JSONB, nullable=False, default=dict)
+    detected_at: Mapped[datetime] = mapped_column(DateTime(timezone=True), nullable=False)
+    resolved_at: Mapped[datetime | None] = mapped_column(DateTime(timezone=True))
+    resolved_by: Mapped[str | None] = mapped_column(String(120))