i18n(not-found): localize 404 page using server-resolved locale

The branded 404 splash hard-coded its three strings in English, ignoring the cookie/Accept-Language locale resolution the rest of the app uses. Switches to getServerTranslator + resolveServerLocale and adds an errors.notFound.{title,body,backToDashboard} block to every locale bundle.

messages/de.json

@@ -152,6 +152,13 @@
     "title": "Da ist etwas schiefgelaufen",
     "description": "Ein unerwarteter Fehler ist aufgetreten. Du kannst es erneut versuchen, die technischen Details kopieren oder einen Bug-Report öffnen."
   },
+  "errors": {
+    "notFound": {
+      "title": "Seite nicht gefunden",
+      "body": "Die gesuchte Seite existiert nicht oder wurde verschoben. Kehr zum Dashboard zurück, um dort weiterzumachen, wo du aufgehört hast.",
+      "backToDashboard": "Zurück zum Dashboard"
+    }
+  },
   "nav": {
     "dashboard": "Dashboard",
     "measurements": "Messungen",

messages/en.json

@@ -152,6 +152,13 @@
     "title": "Something went wrong",
     "description": "An unexpected error occurred. You can retry, copy the technical details, or open a bug report."
   },
+  "errors": {
+    "notFound": {
+      "title": "Page not found",
+      "body": "The page you were looking for doesn't exist or has been moved. Head back to the dashboard to pick up where you left off.",
+      "backToDashboard": "Back to dashboard"
+    }
+  },
   "nav": {
     "dashboard": "Dashboard",
     "measurements": "Measurements",

messages/es.json

@@ -152,6 +152,13 @@
     "title": "Algo ha salido mal",
     "description": "Se ha producido un error inesperado. Puedes reintentar, copiar los detalles técnicos o abrir un reporte de bug."
   },
+  "errors": {
+    "notFound": {
+      "title": "Página no encontrada",
+      "body": "La página que buscas no existe o se ha movido. Vuelve al panel para continuar donde lo dejaste.",
+      "backToDashboard": "Volver al panel"
+    }
+  },
   "nav": {
     "dashboard": "Panel",
     "measurements": "Mediciones",

messages/fr.json

@@ -152,6 +152,13 @@
     "title": "Une erreur est survenue",
     "description": "Une erreur inattendue est survenue. Tu peux réessayer, copier les détails techniques ou ouvrir un rapport de bug."
   },
+  "errors": {
+    "notFound": {
+      "title": "Page introuvable",
+      "body": "La page que tu cherches n’existe pas ou a été déplacée. Reviens au tableau de bord pour reprendre où tu en étais.",
+      "backToDashboard": "Retour au tableau de bord"
+    }
+  },
   "nav": {
     "dashboard": "Tableau de bord",
     "measurements": "Mesures",

messages/it.json

@@ -152,6 +152,13 @@
     "title": "Qualcosa è andato storto",
     "description": "Si è verificato un errore inatteso. Puoi riprovare, copiare i dettagli tecnici o aprire una segnalazione di bug."
   },
+  "errors": {
+    "notFound": {
+      "title": "Pagina non trovata",
+      "body": "La pagina che cercavi non esiste o è stata spostata. Torna alla dashboard per riprendere da dove eri rimasto.",
+      "backToDashboard": "Torna alla dashboard"
+    }
+  },
   "nav": {
     "dashboard": "Dashboard",
     "measurements": "Misurazioni",

messages/pl.json

@@ -152,6 +152,13 @@
     "title": "Coś poszło nie tak",
     "description": "Wystąpił nieoczekiwany błąd. Możesz spróbować ponownie, skopiować szczegóły techniczne lub otworzyć zgłoszenie błędu."
   },
+  "errors": {
+    "notFound": {
+      "title": "Nie znaleziono strony",
+      "body": "Strona, której szukasz, nie istnieje lub została przeniesiona. Wróć do panelu, aby kontynuować od miejsca, w którym przerwałeś.",
+      "backToDashboard": "Powrót do panelu"
+    }
+  },
   "nav": {
     "dashboard": "Panel",
     "measurements": "Pomiary",

src/app/not-found.tsx

@@ -1,6 +1,8 @@
 import Link from "next/link";
 
 import { Logo } from "@/components/ui/logo";
+import { resolveServerLocale } from "@/lib/i18n/server-locale";
+import { getServerTranslator } from "@/lib/i18n/server-translator";
 
 /**
  * v1.4.27 MB6 — branded 404 page. Next.js mounts this file for any
@@ -11,12 +13,19 @@ import { Logo } from "@/components/ui/logo";
  * application error and doesn't need the bug-report path. Just a
  * branded splash with one link home.
  *
+ * v1.4.43 H4 — the copy is locale-resolved server-side from the same
+ * cookie / Accept-Language path the rest of the app uses, so a German
+ * visitor no longer hits an English-only splash on a typo URL.
+ *
  * Mobile-first: `min-h-dvh` follows the dynamic viewport so the
  * panel anchors centred under iOS Safari's animated URL bar;
  * `safe-area-inset-top` keeps the headline clear of the notch or
  * Dynamic Island.
  */
-export default function NotFound() {
+export default async function NotFound() {
+  const locale = await resolveServerLocale();
+  const { t } = getServerTranslator(locale);
+
   return (
     <main
       id="main-content"
@@ -30,18 +39,17 @@ export default function NotFound() {
           404
         </p>
         <h1 className="text-2xl font-bold tracking-tight md:text-3xl">
-          Page not found
+          {t("errors.notFound.title")}
         </h1>
         <p className="text-muted-foreground text-sm leading-relaxed">
-          The page you were looking for doesn&apos;t exist or has been moved.
-          Head back to the dashboard to pick up where you left off.
+          {t("errors.notFound.body")}
         </p>
       </div>
       <Link
         href="/"
         className="bg-primary text-primary-foreground hover:bg-primary/90 inline-flex min-h-11 items-center justify-center rounded-md px-5 text-sm font-medium transition-colors"
       >
-        Back to dashboard
+        {t("errors.notFound.backToDashboard")}
       </Link>
     </main>
   );