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/song-picker.tsx

@@ -0,0 +1,99 @@
+"use client";
+
+import { Loader2, Music } from "lucide-react";
+import { useEffect, useState } from "react";
+import {
+	Select,
+	SelectContent,
+	SelectItem,
+	SelectTrigger,
+	SelectValue,
+} from "@/components/ui/select";
+import {
+	getCachedSongPickerOptions,
+	invalidateSongPickerCache,
+	loadSongPickerOptions,
+	type SoundtrackOption,
+} from "@/lib/client-cache/song-picker-cache";
+
+// Re-export so existing `import { invalidateSongPickerCache } from '.../song-picker'`
+// callsites keep working. New code should import from the lib module directly.
+export { invalidateSongPickerCache };
+
+interface Props {
+	value: number;
+	onChange: (id: number) => void;
+	disabled?: boolean;
+}
+
+function formatLength(seconds: number): string {
+	if (!seconds || seconds <= 0) return "";
+	const m = Math.floor(seconds / 60);
+	const s = seconds % 60;
+	return `${m}:${String(s).padStart(2, "0")}`;
+}
+
+export function SongPicker({ value, onChange, disabled }: Props) {
+	const initial = getCachedSongPickerOptions();
+	const [options, setOptions] = useState<SoundtrackOption[]>(initial ?? []);
+	const [loading, setLoading] = useState(!initial);
+
+	useEffect(() => {
+		if (getCachedSongPickerOptions()) return;
+		let cancelled = false;
+		loadSongPickerOptions()
+			.then((items) => {
+				if (!cancelled) setOptions(items);
+			})
+			.catch(() => {
+				if (!cancelled) setOptions([]);
+			})
+			.finally(() => {
+				if (!cancelled) setLoading(false);
+			});
+		return () => {
+			cancelled = true;
+		};
+	}, []);
+
+	return (
+		<Select
+			value={String(value)}
+			onValueChange={(v) => onChange(parseInt(v, 10) || 0)}
+			disabled={disabled || loading}
+		>
+			<SelectTrigger>
+				{loading ? (
+					<span className="flex items-center gap-2 text-muted-foreground">
+						<Loader2 className="h-3 w-3 animate-spin" /> Loading…
+					</span>
+				) : (
+					<SelectValue placeholder="No song" />
+				)}
+			</SelectTrigger>
+			<SelectContent>
+				<SelectItem value="0">
+					<span className="text-muted-foreground">— No song —</span>
+				</SelectItem>
+				{options.map((opt) => (
+					<SelectItem key={opt.id} value={String(opt.id)}>
+						<span className="inline-flex items-center gap-2">
+							<Music className="h-3 w-3 text-muted-foreground" />
+							<span className="font-medium">{opt.name}</span>
+							{opt.author && (
+								<span className="text-xs text-muted-foreground">
+									— {opt.author}
+								</span>
+							)}
+							{opt.length > 0 && (
+								<span className="text-xs text-muted-foreground font-mono">
+									{formatLength(opt.length)}
+								</span>
+							)}
+						</span>
+					</SelectItem>
+				))}
+			</SelectContent>
+		</Select>
+	);
+}