fix: seed home categories from cache to stop icon flicker

Initialize the categories state from the cached response on first render so the
category icons stay visible when navigating back to the home page, instead of
flashing empty for a frame.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/pages/Home/index.tsx

@@ -45,7 +45,15 @@ export function Home() {
   const { t, lang } = useI18n();
   const lp = useLocalizedPath();
   const { hash } = useLocation();
-  const [cats, setCats] = useState<Category[]>([]);
+  // Seed from cache on the first render so the categories (and their icons)
+  // are present immediately when navigating back to the home page, instead of
+  // flashing empty for a frame before the effect re-applies the cached data.
+  const [cats, setCats] = useState<Category[]>(() => {
+    const cached = readJSONCache<Category[]>(
+      `/api/categories?lang=${encodeURIComponent(langQuery(lang))}`,
+    );
+    return cached ? itemsOrEmpty(cached) : [];
+  });
   const [rec, setRec] = useState<PostBackedResource[]>([]);
   const [latestPosts, setLatestPosts] = useState<Post[]>([]);
   const [popular, setPopular] = useState<PostBackedResource[]>([]);