fix: prevent [object Object] rendering in 25 frontend components

Replace direct {error} JSX rendering with typeof check + .message fallback.
When error is an object (not a string), React showed [object Object].
Now renders error.message or fallback string.

frontend/src/pages/DmsTrash.tsx

@@ -114,7 +114,7 @@ export function DmsTrashPage() {
       <div className="p-6 max-w-7xl mx-auto" data-testid="dms-trash-page">
         <EmptyState
           title={t('dms.error')}
-          description={error}
+          description={typeof error === "string" ? error : (error as any)?.message || "Ein Fehler ist aufgetreten"}
           action={<Button onClick={() => window.location.reload()}>{t('dms.cancel')}</Button>}
         />
       </div>