feat: relocate import tools into studio and harden catalog/furnidata integrity

- Move /admin/import/* tools under /admin/studio/* and add studio nav, layout and tabs
- Add shared catalog maintenance panel plus a /admin/studio/maintenance tab
- Make furnidata reconciliation overwrite conflicting entries with the
  DB-authoritative items_base classname/id (surfaced via fixedConflicts)
- Add furnidata_translate_enabled setting to skip the heavy localized
  furnidata build during import (manual build-languages still forces it)
- Update staff smoke contract test for the studio hub

src/app/admin/studio/furni/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 StudioFurniPage(_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}
+		/>
+	);
+}