perf(studio): virtualize the furniture table and throttle batch progress

- Render the table view through a virtualizer too, using a shared grid
  template so the sticky header and rows keep perfect column alignment
- Keep semantic table/row/cell elements while virtualizing
- Cap the batch item-details list to the latest 60 rows (newest first)
- Coalesce per-item progress events server-side (120ms throttle) in both
  the exact-import and clone SSE batch runners

src/components/admin/studio/batch-progress.tsx

@@ -73,7 +73,13 @@ export const BatchProgress = memo(function BatchProgress({
 		return () => clearInterval(id);
 	}, [done]);
 
-	const entries = useMemo(() => [...progress.values()], [progress]);
+	// Relevance-first list: newest activity on top, capped so high-volume
+	// imports don't render hundreds of DOM rows on every progress event.
+	const VISIBLE_ITEMS = 60;
+	const entries = useMemo(
+		() => [...progress.values()].slice().reverse(),
+		[progress],
+	);
 	const completed = useMemo(
 		() =>
 			entries.filter((i) => i.status === "done" || i.status === "failed")
@@ -239,7 +245,12 @@ export const BatchProgress = memo(function BatchProgress({
 					View item details ({total})
 				</summary>
 				<div className="mt-2 max-h-44 space-y-2 overflow-auto">
-					{entries.map((item) => (
+					{entries.length > VISIBLE_ITEMS && (
+						<p className="px-1 text-[0.65rem] text-[var(--admin-text-muted)]">
+							Showing {VISIBLE_ITEMS} of {entries.length} items
+						</p>
+					)}
+					{entries.slice(0, VISIBLE_ITEMS).map((item) => (
 						<div
 							key={item.classname}
 							className="flex items-start gap-2 rounded-md bg-[var(--admin-canvas)] p-2 text-xs"