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/components/Layout.tsx

@@ -10,6 +10,7 @@ import { DemoGuide, DemoGuideTrigger } from "./DemoGuide";
 import { LanguageSwitcher } from "./LanguageSwitcher";
 import { useDemoGuide } from "../context/DemoGuideContext";
 import { useDemoManifest } from "../context/DemoManifestContext";
+import { PRODUCT_NAME } from "../product";
 
 const SEARCH_ICON: Record<SearchResultItem["type"], IconName> = {
   vehicle: "fleet",
@@ -18,6 +19,31 @@ const SEARCH_ICON: Record<SearchResultItem["type"], IconName> = {
   section: "chevron",
 };
 
+// The backend only ever sends a stable code + raw data params (never English prose) --
+// see app/api/routers/search.py. Localizing here means the label/detail always follow
+// the operator's selected locale, in every namespace search results can point to.
+function searchResultLabel(t: (key: string, opts?: Record<string, unknown>) => string, item: SearchResultItem): string {
+  if (item.type === "section") return t(`navigation:items.${item.label}`, { defaultValue: item.label });
+  return item.label;
+}
+
+function searchResultDetail(t: (key: string, opts?: Record<string, unknown>) => string, item: SearchResultItem): string {
+  switch (item.type) {
+    case "section":
+      return t(`searchSections.${item.detail_code}`, { defaultValue: item.detail_code });
+    case "vehicle":
+      return t("searchVehicleSummary", { ...item.detail_params });
+    case "booking":
+      return t(`bookings:statuses.${item.detail_code}`, { defaultValue: item.detail_code });
+    case "data_quality_issue":
+      return t(`quality:ruleTypes.${item.detail_code}`, {
+        defaultValue: item.detail_code.replace(/_/g, " "),
+      });
+    default:
+      return item.detail_code;
+  }
+}
+
 interface NavItem {
   to: string;
   labelKey: string;
@@ -177,7 +203,7 @@ export function Layout() {
       <aside className={`sidebar ${mobileOpen ? "is-open" : ""}`}>
         <div className="brand-lockup">
           <BrandMark className="brand-mark" />
-          <div><strong>{t("common:appName")}</strong><span>{t("common:brandTagline")}</span></div>
+          <div><strong>{PRODUCT_NAME}</strong><span>{t("common:brandTagline")}</span></div>
         </div>
         <div className="sidebar-language">
           <LanguageSwitcher />
@@ -234,7 +260,7 @@ export function Layout() {
           </button>
           <div className="global-search" role="search" ref={searchBox}>
             <Icon name="search" />
-            <label className="visually-hidden" htmlFor="global-search-input">{t("searchLabel")}</label>
+            <label className="visually-hidden" htmlFor="global-search-input">{t("searchLabel", { productName: PRODUCT_NAME })}</label>
             <input
               id="global-search-input"
               ref={searchInput}
@@ -276,8 +302,8 @@ export function Layout() {
                     >
                       <Icon name={SEARCH_ICON[item.type]} />
                       <span className="search-result-copy">
-                        <strong>{item.label}</strong>
-                        <small>{item.detail}</small>
+                        <strong>{searchResultLabel(t, item)}</strong>
+                        <small>{searchResultDetail(t, item)}</small>
                       </span>
                     </button>
                   ))}
@@ -302,7 +328,7 @@ export function Layout() {
         </header>
 
         <main id="main-content" tabIndex={-1}><Outlet /></main>
-        <footer className="app-footer"><span>{t("common:footer.productLine")}</span><span>{t("common:footer.locale")}</span></footer>
+        <footer className="app-footer"><span>{t("common:footer.productLine", { productName: PRODUCT_NAME })}</span><span>{t("common:footer.locale")}</span></footer>
       </div>
 
       <nav className="mobile-nav" aria-label={t("mobileNavLabel")}>