Quiz list: drill down by Books → book and Lectures → year

The All tab is now a click-through of category cards — Books, Lectures &
Conversations, Other quizzes — each opening its books or years, then the
quizzes themselves. Only categories with quizzes get a card. The position
and tab live in the URL (?in=books&book=bg, ?tab=todo), so refresh, Back
and shared links keep your place. Book quizzes list in chapter order.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

app/(app)/quizzes/page.tsx

@@ -1,3 +1,4 @@
+import { Suspense } from "react";
 import type { Metadata } from "next";
 import { ogForQuizzes } from "@/lib/og";
 import { QuizzesList } from "./quizzes-list";
@@ -10,5 +11,11 @@ export const metadata: Metadata = {
 };
 
 export default function QuizzesPage() {
-  return <QuizzesList />;
+  // The list reads its tab and category from the URL (useSearchParams),
+  // which needs a Suspense boundary to render.
+  return (
+    <Suspense fallback={null}>
+      <QuizzesList />
+    </Suspense>
+  );
 }