fix(web): authorities unknown-kind redirect, extract labelText util, EN-required test

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

web/src/lib/labels.ts

@@ -0,0 +1,12 @@
+import type { components } from "../api/schema";
+
+type LabelView = components["schemas"]["LabelView"];
+
+export function labelText(labels: LabelView[], lang: string): string {
+  return (
+    labels.find((l) => l.lang === lang)?.label ??
+    labels.find((l) => l.lang === "en")?.label ??
+    labels[0]?.label ??
+    ""
+  );
+}