Replace standalone catalog editor with the unified Visual Catalog studio

Make /admin/catalog a full-screen catalog studio that replaces the old
listing plus separate [id]/builder-club detail pages:

- Embed CatalogManagerWorkspace on /admin/catalog with a Normal/Builder
  Club toggle, Catalog Sync status, packages (normal), Organize imports
  and a diagnostics link to /admin/studio/maintenance.
- Manage BC items directly in the studio Items tab (new BcItemsEditor,
  CRUD via existing bc actions; /api/admin/catalog/items now serves BC).
- Inline editor: add pageTextTeaser field for both catalogs and remove
  the legacy full-editor links.
- Remove the 'Open full editor' context action from the tree.
- Move catalog-items-table (dir + barrel) and catalog-translate-tab out
  of the app route into src/components/admin/catalog and update all
  importers.
- Keep /admin/catalog/[id], builder-club/[id] and /admin/catalog/maintenance
  as redirects into the new studio; consolidate maintenance panels into
  /admin/studio/maintenance and point the nav item there.
- Delete the old listing/table/tabs/forms and the standalone bc-manager.

src/components/admin/catalog/catalog-items-table/furni-icon.tsx

@@ -0,0 +1,48 @@
+"use client";
+
+import { Image as ImageIcon } from "lucide-react";
+import { getHabboCdnIconUrl, getLocalIconUrl } from "@/lib/furni/classname";
+
+export function FurniIcon({
+	classname,
+	revision,
+}: {
+	classname: string;
+	revision: number;
+}) {
+	if (!classname) {
+		return (
+			<div className="w-10 h-10 rounded bg-muted flex items-center justify-center">
+				<ImageIcon className="h-4 w-4 text-muted-foreground" />
+			</div>
+		);
+	}
+
+	const localUrl = getLocalIconUrl(classname);
+
+	function handleError(e: React.SyntheticEvent<HTMLImageElement>) {
+		const img = e.target as HTMLImageElement;
+		const stage = img.dataset.fallback;
+		if (!stage && revision > 0) {
+			img.dataset.fallback = "cdn";
+			img.src = getHabboCdnIconUrl(classname, revision);
+		} else {
+			img.dataset.fallback = "none";
+			img.style.opacity = "0";
+		}
+	}
+
+	return (
+		<div className="w-10 h-10 rounded bg-muted/50 flex items-center justify-center overflow-hidden">
+			{/* eslint-disable-next-line @next/next/no-img-element */}
+			<img
+				src={localUrl}
+				alt={classname}
+				className="max-w-full max-h-full object-contain"
+				style={{ imageRendering: "pixelated" }}
+				onError={handleError}
+				loading="lazy"
+			/>
+		</div>
+	);
+}