fix: safe status-recommendation flow, MO-016 order independence, brand constant, message codes

- Add a single shared, pure vehicle-status evaluator (app/services/vehicle_status.py)
  used identically by the data-quality scanner, a new non-mutating status-recommendation
  preview endpoint, and a transactional apply endpoint with optimistic-concurrency token
  revalidation -- eliminates the old opaque "calculate and apply" action and the unsafe
  "maintenance + active booking -> auto rented" shortcut. Frontend
  DataQualityIssueDetail.tsx now shows a review/decide/confirm panel with localized
  why/evidence/consequence text in nl-BE/en-GB/fr-BE, with an exact "Change status to
  <status>" confirm action per the brief.
- Fix MO-016 issue-order dependency: resolving the booking-overlap issue before vs.
  after the status-conflict issue now converges on the same final vehicle status,
  proven by test_mo_016_status_conflict_recommendation_is_order_independent.
- Make "Fleet Ops" a non-localizable brand constant (frontend/src/product.ts,
  backend PRODUCT_NAME) via {{productName}} interpolation everywhere the brand name
  appeared in locale prose; add a permanent test guarding against a translation file
  ever defining the brand name or an "appName" key again.
- Convert dynamic backend prose to stable message codes + params: return status
  reasons, audit field/actor-type labels, automation last_error, and search
  section/vehicle/booking/issue results all now carry codes the frontend localizes,
  with raw technical text demoted to a "Technical details" disclosure.
- docs/fleet-ops-correction/: gap audit, i18n inventory, and the vehicle-status
  decision table documenting the evaluator's rules and safe-status principles.

148 backend tests + Ruff + mypy green; Alembic migration verified upgrade/downgrade;
frontend tsc/build and the i18n-coverage Playwright suite green.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backend/tests/test_vehicle_status.py

@@ -0,0 +1,160 @@
+"""Pure unit tests for the shared vehicle-status evaluator -- no database needed, since
+evaluate_vehicle_status() only reasons over an already-gathered VehicleStatusFacts. See
+docs/fleet-ops-correction/vehicle-status-decision-table.md for the decision table these
+tests are asserting against."""
+
+from types import SimpleNamespace
+
+from app.services.vehicle_status import (
+    RECOMMENDATION_CODE_ACTIVE_RENTAL,
+    RECOMMENDATION_CODE_BOOKING_CONFLICT,
+    RECOMMENDATION_CODE_MANUAL_REVIEW,
+    RECOMMENDATION_CODE_NO_CONFLICT,
+    RECOMMENDATION_CODE_RENTAL_ENDED,
+    RECOMMENDATION_CODE_SERVICE_THRESHOLD,
+    VehicleStatusFacts,
+    compute_recommendation_token,
+    evaluate_vehicle_status,
+)
+
+
+def _vehicle(status: str, *, version: int = 1):
+    return SimpleNamespace(operational_status=status, version=version)
+
+
+def _facts(**overrides) -> VehicleStatusFacts:
+    defaults = dict(
+        active_booking_refs=[],
+        overlapping_booking_pairs=[],
+        service_threshold_reached=False,
+        odometer_km=10_000,
+        next_service_km=20_000,
+        open_booking_overlap_issue_ref=None,
+    )
+    defaults.update(overrides)
+    return VehicleStatusFacts(**defaults)
+
+
+def test_available_with_active_rental_recommends_rented():
+    result = evaluate_vehicle_status(
+        _vehicle("available"), _facts(active_booking_refs=["BK-0001"])
+    )
+    assert result.recommended_status == "rented"
+    assert result.recommendation_code == RECOMMENDATION_CODE_ACTIVE_RENTAL
+    assert result.safe_to_apply is True
+    assert result.manual_review_required is False
+
+
+def test_maintenance_with_active_rental_never_auto_recommends_rented():
+    # The exact unsafe shortcut this task explicitly forbids: maintenance + an active
+    # booking must NEVER be auto-resolved to "rented".
+    result = evaluate_vehicle_status(
+        _vehicle("maintenance"), _facts(active_booking_refs=["BK-0001"])
+    )
+    assert result.recommended_status is None
+    assert result.manual_review_required is True
+    assert result.safe_to_apply is False
+    assert result.recommendation_code == RECOMMENDATION_CODE_MANUAL_REVIEW
+
+
+def test_available_with_active_rental_and_service_threshold_requires_manual_review():
+    result = evaluate_vehicle_status(
+        _vehicle("available"),
+        _facts(active_booking_refs=["BK-0001"], service_threshold_reached=True),
+    )
+    assert result.manual_review_required is True
+    assert result.recommended_status is None
+
+
+def test_available_with_active_rental_and_booking_conflict_requires_manual_review():
+    result = evaluate_vehicle_status(
+        _vehicle("available"),
+        _facts(active_booking_refs=["BK-0001"], open_booking_overlap_issue_ref="DQ-0001"),
+    )
+    assert result.manual_review_required is True
+    assert result.recommended_status is None
+
+
+def test_rented_with_no_active_booking_recommends_available():
+    result = evaluate_vehicle_status(_vehicle("rented"), _facts())
+    assert result.recommended_status == "available"
+    assert result.recommendation_code == RECOMMENDATION_CODE_RENTAL_ENDED
+    assert result.safe_to_apply is True
+
+
+def test_service_threshold_reached_recommends_maintenance():
+    result = evaluate_vehicle_status(
+        _vehicle("available"), _facts(service_threshold_reached=True)
+    )
+    assert result.recommended_status == "maintenance"
+    assert result.recommendation_code == RECOMMENDATION_CODE_SERVICE_THRESHOLD
+
+
+def test_booking_conflict_recommends_blocked_not_a_generic_high_severity_proxy():
+    # The evaluator must react to a *real* booking-conflict fact, not "does some other
+    # open high-severity issue happen to exist" (the forbidden proxy).
+    result = evaluate_vehicle_status(
+        _vehicle("available"),
+        _facts(overlapping_booking_pairs=[("BK-DEMO-OVERLAP-A", "BK-DEMO-OVERLAP-B")]),
+    )
+    assert result.recommended_status == "blocked"
+    assert result.recommendation_code == RECOMMENDATION_CODE_BOOKING_CONFLICT
+
+
+def test_open_booking_overlap_issue_alone_also_triggers_blocked():
+    result = evaluate_vehicle_status(
+        _vehicle("available"), _facts(open_booking_overlap_issue_ref="DQ-DEMO-OVERLAP")
+    )
+    assert result.recommended_status == "blocked"
+    assert result.recommendation_code == RECOMMENDATION_CODE_BOOKING_CONFLICT
+
+
+def test_maintenance_with_no_active_rental_and_no_blockers_stays_manual():
+    # No fact here confirms maintenance is actually finished, so the evaluator must not
+    # auto-clear it to "available" -- that release remains an explicit, manual decision.
+    result = evaluate_vehicle_status(_vehicle("maintenance"), _facts())
+    assert result.recommended_status is None
+    assert result.recommendation_code == RECOMMENDATION_CODE_NO_CONFLICT
+    assert result.safe_to_apply is False
+
+
+def test_no_conflict_when_status_already_matches_facts():
+    result = evaluate_vehicle_status(_vehicle("available"), _facts())
+    assert result.recommended_status is None
+    assert result.recommendation_code == RECOMMENDATION_CODE_NO_CONFLICT
+    assert result.safe_to_apply is False
+
+    result = evaluate_vehicle_status(_vehicle("rented"), _facts(active_booking_refs=["BK-1"]))
+    assert result.recommendation_code == RECOMMENDATION_CODE_NO_CONFLICT
+
+    result = evaluate_vehicle_status(_vehicle("blocked"), _facts())
+    assert result.recommendation_code == RECOMMENDATION_CODE_NO_CONFLICT
+
+    result = evaluate_vehicle_status(
+        _vehicle("maintenance"), _facts(service_threshold_reached=True)
+    )
+    assert result.recommendation_code == RECOMMENDATION_CODE_NO_CONFLICT
+
+
+def test_recommendation_token_changes_when_facts_change():
+    vehicle = _vehicle("available")
+    facts_a = _facts()
+    facts_b = _facts(service_threshold_reached=True)
+    assert compute_recommendation_token(vehicle, facts_a) != compute_recommendation_token(
+        vehicle, facts_b
+    )
+
+
+def test_recommendation_token_is_stable_for_identical_facts():
+    vehicle = _vehicle("available")
+    facts = _facts(active_booking_refs=["BK-0001"])
+    assert compute_recommendation_token(vehicle, facts) == compute_recommendation_token(
+        vehicle, facts
+    )
+
+
+def test_recommendation_token_changes_when_vehicle_version_changes():
+    facts = _facts()
+    assert compute_recommendation_token(
+        _vehicle("available", version=1), facts
+    ) != compute_recommendation_token(_vehicle("available", version=2), facts)