i18n: Fix last hardcoded German error string in export function

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/static/js/app.js

@@ -2032,7 +2032,7 @@ const App = {
             const response = await API.exportIncident(this.currentIncidentId, format, scope);
             if (!response.ok) {
                 const err = await response.json().catch(() => ({}));
-                throw new Error(err.detail || 'Fehler ' + response.status);
+                throw new Error(err.detail || LangManager.t('err.generic') + ' ' + response.status);
             }
             const blob = await response.blob();
             const disposition = response.headers.get('Content-Disposition') || '';

src/static/js/lang.js

@@ -392,6 +392,7 @@ const TRANSLATIONS = {
   'err.verification_failed':   { de: 'Verifikation fehlgeschlagen',                                       en: 'Verification failed' },
   'err.request_failed':        { de: 'Anfrage fehlgeschlagen',                                             en: 'Request failed' },
   'err.verification_check_failed': { de: 'Verifizierung fehlgeschlagen',                                  en: 'Verification failed' },
+  'err.generic':               { de: 'Fehler',                                                              en: 'Error' },
 
   // ── Fact check status (for notifications) ──────────────
   'fc_status.confirmed':       { de: 'Bestätigt',                                                          en: 'Confirmed' },