feat: enhance accessibility and testing with data-test attributes and improve error handling

apps/web/app/[locale]/home/[account]/finance/sepa/[batchId]/page.tsx

@@ -74,7 +74,7 @@ export default async function SepaBatchDetailPage({ params }: PageProps) {
     api.getBatchItems(batchId),
   ]);
 
-  if (!batch) return <div>Einzug nicht gefunden</div>;
+  if (!batch) return <AccountNotFound />;
 
   const status = String(batch.status);