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/app/services/dispatcher.py

@@ -48,6 +48,7 @@ def _reclaim_stale_deliveries(batch_size: int = 10) -> int:
                 f"(no outcome recorded within {settings.n8n_delivery_lease_seconds:.0f}s; "
                 f"the process likely crashed mid-delivery). attempts preserved at {row.attempts}."
             )[:2000]
+            row.last_error_code = "staleLeaseRecovered"
         db.commit()
         return len(rows)
     finally:
@@ -111,8 +112,10 @@ def _deliver_one(event_id: uuid.UUID) -> None:
     finally:
         db.close()
 
+    error_code: str | None
     if wire_event is None:
         success, error, body = False, payload_error, None
+        error_code = "malformedPayload"
     else:
         try:
             response = httpx.post(
@@ -124,9 +127,11 @@ def _deliver_one(event_id: uuid.UUID) -> None:
             body = response.json()
             success = bool(body.get("ok", True))
             error = None if success else f"n8n reported failure: {body}"
+            error_code = None if success else "remoteReportedFailure"
         except httpx.HTTPError as exc:
             success = False
             error = f"{type(exc).__name__}: {exc}"
+            error_code = "connectionError"
             body = None
 
     db = SessionLocal()
@@ -138,10 +143,12 @@ def _deliver_one(event_id: uuid.UUID) -> None:
         if success:
             event.delivery_status = "succeeded"
             event.last_error = None
+            event.last_error_code = None
             event.next_attempt_at = None
             event.external_run_id = str((body or {}).get("event_id", event_id))
         else:
             event.last_error = (error or "delivery failed")[:2000]
+            event.last_error_code = error_code or "unknownError"
             if event.attempts >= settings.n8n_max_attempts:
                 event.delivery_status = "failed"
                 event.next_attempt_at = None