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/api/staff/route.ts

@@ -1,6 +1,7 @@
 import { asc, desc, gte } from "drizzle-orm";
 import { apiJson } from "@/lib/api";
 import { db, User } from "@/lib/db";
+import { apiCacheKey, redisCache } from "@/lib/redis-cache";
 import { siteSettings } from "@/lib/services/site-settings";
 
 // Public REST API — staff list. Mirrors src/app/staff/page.tsx: users whose
@@ -11,17 +12,19 @@ export async function GET(_req: Request) {
 		const minStaffRank =
 			Number(await siteSettings.get("min_staff_rank", "7")) || 7;
 
-		const staff = await db
-			.select({
-				username: User.username,
-				look: User.look,
-				rank: User.rank,
-				motto: User.motto,
-			})
-			.from(User)
-			.where(gte(User.rank, minStaffRank))
-			.orderBy(desc(User.rank), asc(User.username))
-			.limit(100);
+		const staff = await redisCache(apiCacheKey("staff"), 300, () =>
+			db
+				.select({
+					username: User.username,
+					look: User.look,
+					rank: User.rank,
+					motto: User.motto,
+				})
+				.from(User)
+				.where(gte(User.rank, minStaffRank))
+				.orderBy(desc(User.rank), asc(User.username))
+				.limit(100),
+		);
 
 		return apiJson({ data: staff }, { status: 200 });
 	} catch {