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/radio/current-dj/route.ts

@@ -1,33 +1,46 @@
 import { eq } 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";
 
 // Current on-air DJ. The DJ is set manually via the radio_current_dj_id setting
 // (Manual DJ user ID). When set, resolve that user's username/look; otherwise
 // there is no DJ on air. Mirrors the AtomCMS radio "on air" widget.
 
+// The radio widget polls this endpoint frequently — a short cache avoids a DB
+// hit per poll. The DJ only changes when a moderator switches it manually.
+const GET_TTL_SECONDS = 5;
+
 export async function GET(_req: Request) {
 	try {
-		const raw = await siteSettings.get("radio_current_dj_id", "");
-		const id = Number(raw);
+		const dj = await redisCache(
+			apiCacheKey("radio:current-dj"),
+			GET_TTL_SECONDS,
+			async () => {
+				const raw = await siteSettings.get("radio_current_dj_id", "");
+				const id = Number(raw);
 
-		// No DJ configured (empty / non-numeric / zero).
-		if (!raw || !Number.isFinite(id) || id <= 0) {
-			return apiJson({ dj: null });
-		}
+				// No DJ configured (empty / non-numeric / zero).
+				if (!raw || !Number.isFinite(id) || id <= 0) {
+					return null;
+				}
 
-		const [user] = await db
-			.select({ username: User.username, look: User.look })
-			.from(User)
-			.where(eq(User.id, id))
-			.limit(1);
+				const [user] = await db
+					.select({ username: User.username, look: User.look })
+					.from(User)
+					.where(eq(User.id, id))
+					.limit(1);
 
-		if (!user) {
-			return apiJson({ dj: null });
-		}
+				if (!user) {
+					return null;
+				}
 
-		return apiJson({ dj: { username: user.username, look: user.look } });
+				return { username: user.username, look: user.look };
+			},
+		);
+
+		return apiJson({ dj });
 	} catch {
 		// DB / settings unavailable — no DJ rather than a 500.
 		return apiJson({ dj: null }, { status: 200 });