Add all-in-one Studio merging furni import and catalog management

Add a full-viewport /admin/studio workspace that unifies the import and
catalog systems into a single automated flow:

- Furni library browser against official Habbo furnidata with search,
  type/status filters, live previews and pagination
- Catalog structure rail showing where imported furniture lands
- Detail drawer with automatic placement preview (category + price via
  classifyFurni/autoPriceFurni) and one-click import that downloads
  assets, converts SWF to nitro, writes items_base, updates
  FurnitureData.json and creates an auto-priced catalog entry
- Batch auto-import with SSE progress and RCON cache refresh
- Nitro editor integration and imported-item deletion

Extract pure auto-catalog helpers (CATEGORY_PAGE, CLASSNAME_RULES,
classifyFurni, autoPriceFurni) into a client-safe module shared by the
server pipeline and the Studio UI so the preview always matches what the
emulator import applies.

src/app/admin/studio/page.tsx

@@ -0,0 +1,27 @@
+import { redirect } from "next/navigation";
+import { StudioClient } from "@/components/admin/studio/studio-client";
+import { buildFurniImportSource } from "@/lib/habbo-gamedata-hotel";
+import { canAccess, getAdminContext, PERMS } from "@/lib/permissions";
+import { getTreeFlat } from "@/lib/services/catalog-tree";
+import { getHabboGamedataHotel } from "@/lib/services/habbo-gamedata-hotel";
+
+export default async function StudioPage(_props: {
+	params: Promise<{ locale: string }>;
+}) {
+	const { session, permissions } = await getAdminContext();
+	if (!canAccess(permissions, PERMS.ASSETS_IMPORT, session.user.rank)) {
+		redirect("/admin");
+	}
+
+	const [hotel, catalogTree] = await Promise.all([
+		getHabboGamedataHotel(),
+		getTreeFlat(),
+	]);
+
+	return (
+		<StudioClient
+			source={buildFurniImportSource(hotel)}
+			initialTree={catalogTree}
+		/>
+	);
+}