Add performance optimizations and component refactors

- Cache read-heavy public API routes via redisCache (leaderboard, values,
  shop, articles, photos, guilds, teams, staff, users, home, radio, badges)
- Add single-flight and bounded-memory cache layer with unit tests
- Parallelize independent DB queries on search, rares, shop, staff, polls
  and profile pages
- Push radio points leaderboard aggregation to SQL with a LIMIT
- Split studio-client and import-furni-client into focused modules
- Clean up next.config.ts

src/app/(site)/shop/page.tsx

@@ -112,38 +112,30 @@ export default async function ShopPage({
 				: t("success.bought")
 			: null;
 
-	// Categories for the filter bar.
-	let categories: ShopCategory[] = [];
-	try {
-		categories = await db
+	// Categories for the filter bar and the article grid are independent —
+	// fetch them concurrently.
+	const [categories, articles] = await Promise.all([
+		db
 			.select({
 				id: WebsiteShopCategories.id,
 				name: WebsiteShopCategories.name,
 				icon: WebsiteShopCategories.icon,
 			})
 			.from(WebsiteShopCategories)
-			.orderBy(asc(WebsiteShopCategories.name));
-	} catch {
-		categories = [];
-	}
-
-	let articles: ShopArticle[] = [];
-	try {
-		if (categoryId) {
-			articles = await db
-				.select(articleSelect)
-				.from(WebsiteShopArticles)
-				.where(eq(WebsiteShopArticles.categoryId, BigInt(categoryId)))
-				.orderBy(asc(WebsiteShopArticles.position));
-		} else {
-			articles = await db
-				.select(articleSelect)
-				.from(WebsiteShopArticles)
-				.orderBy(asc(WebsiteShopArticles.position));
-		}
-	} catch {
-		articles = [];
-	}
+			.orderBy(asc(WebsiteShopCategories.name))
+			.catch((): ShopCategory[] => []),
+		(categoryId
+			? db
+					.select(articleSelect)
+					.from(WebsiteShopArticles)
+					.where(eq(WebsiteShopArticles.categoryId, BigInt(categoryId)))
+					.orderBy(asc(WebsiteShopArticles.position))
+			: db
+					.select(articleSelect)
+					.from(WebsiteShopArticles)
+					.orderBy(asc(WebsiteShopArticles.position))
+		).catch((): ShopArticle[] => []),
+	]);
 
 	const activeCategory = categoryId
 		? categories.find((c) => String(c.id) === categoryId)