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>

frontend/src/styles.css

@@ -273,6 +273,14 @@ details summary { cursor: pointer; color: var(--teal-dark); }.data-table details
 .scenario-callout strong { display: block; margin-bottom: 4px; color: var(--ink); font-size: .82rem; }
 .scenario-callout p { margin: 0; color: var(--ink-soft); font-size: .78rem; line-height: 1.55; }
 
+.status-decision { margin-top: 16px; padding: 16px 18px; background: var(--surface-subtle); border: 1px solid var(--line); border-radius: var(--radius); }
+.status-decision h3 { margin: 16px 0 6px; color: var(--ink); font-size: .72rem; font-weight: 700; text-transform: uppercase; letter-spacing: .05em; }
+.status-decision h3:first-child { margin-top: 0; }
+.status-decision > .detail-grid { margin-bottom: 4px; }
+.evidence-list { margin: 0; padding-left: 18px; color: var(--ink-soft); font-size: .78rem; line-height: 1.6; }
+.evidence-list li { margin-bottom: 2px; }
+.status-decision .button { margin-top: 16px; }
+
 .duplicate-compare { margin-top: 18px; }.duplicate-compare fieldset { margin: 15px 0; padding: 13px; border: 1px solid var(--line); }.duplicate-compare legend { padding: 0 5px; color: var(--ink-soft); font-size: .69rem; font-weight: 700; }.duplicate-compare fieldset label { display: inline-flex !important; margin-right: 18px; }
 .compare-table th, .compare-table td { vertical-align: top; }.compare-table label { display: inline-flex; flex-direction: row; align-items: center; gap: 6px; }.difference-mark, .match-mark { display: block; width: max-content; margin-top: 4px; padding: 2px 5px; font-size: .52rem; border-radius: 2px; }.difference-mark { color: var(--warning); background: var(--warning-pale); }.match-mark { color: var(--success); background: var(--success-pale); }
 .merge-preview { padding: 13px; color: var(--ink-soft); background: var(--surface-subtle); border-left: 3px solid var(--teal); font-size: .75rem; }.duplicate-compare > button { color: white; background: var(--teal-dark); border-color: var(--teal-dark); }