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/components/admin/studio/catalog-rail.tsx

@@ -0,0 +1,103 @@
+"use client";
+
+import { ChevronDown, ChevronRight, FolderTree } from "lucide-react";
+import { useMemo, useState } from "react";
+
+import { cn } from "@/lib/utils";
+import type { TreeNode } from "@/types/catalog";
+
+export function CatalogRail({
+	tree,
+	selectedId,
+	onSelect,
+}: {
+	tree: TreeNode[];
+	selectedId: number | null;
+	onSelect: (id: number | null) => void;
+}) {
+	const [collapsed, setCollapsed] = useState<Set<number>>(new Set());
+
+	const visible = useMemo(() => {
+		const hidden = new Set<number>();
+		for (const node of tree) {
+			if (hidden.has(node.parentId)) {
+				hidden.add(node.id);
+				continue;
+			}
+			if (collapsed.has(node.parentId)) {
+				hidden.add(node.id);
+			}
+		}
+		return tree.filter((n) => !hidden.has(n.id));
+	}, [tree, collapsed]);
+
+	const toggle = (id: number) => {
+		setCollapsed((prev) => {
+			const next = new Set(prev);
+			if (next.has(id)) next.delete(id);
+			else next.add(id);
+			return next;
+		});
+	};
+
+	return (
+		<aside className="flex h-full min-h-0 w-64 shrink-0 flex-col border-r border-[var(--admin-border)] bg-[var(--admin-surface)]">
+			<div className="flex items-center gap-2 border-b border-[var(--admin-border)] px-3 py-2.5">
+				<FolderTree size={14} className="text-[var(--admin-accent)]" />
+				<span className="text-xs font-bold uppercase tracking-wider text-[var(--admin-text-muted)]">
+					Catalog
+				</span>
+			</div>
+			<div className="min-h-0 flex-1 overflow-y-auto p-1.5">
+				{visible.length === 0 ? (
+					<p className="px-2 py-4 text-xs text-[var(--admin-text-muted)]">
+						No catalog pages found.
+					</p>
+				) : (
+					visible.map((node) => {
+						const isRoot = node.parentId <= 0;
+						const hasChildren = node.childCount > 0;
+						const isCollapsed = collapsed.has(node.id);
+						return (
+							<button
+								key={node.id}
+								type="button"
+								onClick={() => {
+									if (hasChildren) toggle(node.id);
+									onSelect(selectedId === node.id ? null : node.id);
+								}}
+								className={cn(
+									"group flex w-full items-center gap-1.5 rounded-md px-1.5 py-1.5 text-left text-xs transition-colors",
+									selectedId === node.id
+										? "bg-[var(--admin-accent)]/15 text-[var(--admin-text)]"
+										: "text-[var(--admin-text-muted)] hover:bg-[var(--admin-accent)]/10 hover:text-[var(--admin-text)]",
+								)}
+								style={{ paddingLeft: `${6 + node.depth * 12}px` }}
+							>
+								{hasChildren ? (
+									isCollapsed ? (
+										<ChevronRight size={12} className="shrink-0" />
+									) : (
+										<ChevronDown size={12} className="shrink-0" />
+									)
+								) : (
+									<span className="w-3 shrink-0" />
+								)}
+								<span className="min-w-0 flex-1 truncate">
+									{isRoot ? (
+										<span className="font-semibold">{node.caption}</span>
+									) : (
+										node.caption
+									)}
+								</span>
+								<span className="shrink-0 rounded-full bg-[var(--admin-accent)]/10 px-1.5 text-[0.6rem] font-semibold text-[var(--admin-accent)]">
+									{node.itemCount}
+								</span>
+							</button>
+						);
+					})
+				)}
+			</div>
+		</aside>
+	);
+}