feat: Studio bulk ops, perf fixes, bug fixes, confirm dialog visibility

Confirm Dialog:
- Overlay opacity 80% -> 95% (solid black)
- Card uses bg-surface with glow shadow ring-primary/40
- Added AlertTriangle icon for danger variant
- Removed backdrop-blur for maximum opacity

Studio features:
- Bulk delete: select imported items and delete in batch
- Bulk nitro regen: select items missing .nitro and regenerate all
- Added Trash2 and RefreshCw toolbar buttons for bulk actions

Performance:
- BatchProgress: React.memo + useMemo for entries/total/completed/percent
- BatchProgress: ETA interval uses useRef to avoid re-creation per completed
- CatalogRail: React.memo + useCallback for toggle
- Removed redundant double setBatchProgress calls
- Removed redundant new Map(initial) wrapping

Bug fixes:
- importBatch: stale batchDone closure always cleared progress panel (use ref)
- importBatch: added missing toast.error on HTTP failure
- bulkRegenNitro: now checks per-item results instead of marking all as succeeded
- single deleteItem: now removes classname from selected set
- retryFailed: clears progress panel on HTTP error and stream error
- Removed unused 'done' variable (2x) from cloneAllMissing/retryFailed

Lint:
- biome format fixes for selectedMissingNitro and setItems

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

@@ -1,7 +1,7 @@
 "use client";
 
 import { Ban, Check, Loader2, ShieldCheck, X } from "lucide-react";
-import { useEffect, useState } from "react";
+import { memo, useEffect, useMemo, useRef, useState } from "react";
 
 import { Button } from "@/components/ui/button";
 import { cn } from "@/lib/utils";
@@ -40,7 +40,7 @@ function formatEta(ms: number): string {
 	return `${min}m ${sec}s`;
 }
 
-export function BatchProgress({
+export const BatchProgress = memo(function BatchProgress({
 	progress,
 	done,
 	succeeded,
@@ -65,33 +65,42 @@ export function BatchProgress({
 	onDismiss?: () => void;
 	onRetry?: (classnames: string[]) => void;
 }) {
-	const entries = [...progress.entries()];
-	const total = entries.length;
-	const completed = entries.filter(
-		([, s]) => s.status === "done" || s.status === "failed",
-	).length;
-	const percent = total > 0 ? Math.round((completed / total) * 100) : 0;
+	const { entries, total, completed, percent } = useMemo(() => {
+		const e = [...progress.entries()];
+		const t = e.length;
+		const c = e.filter(
+			([, s]) => s.status === "done" || s.status === "failed",
+		).length;
+		return {
+			entries: e,
+			total: t,
+			completed: c,
+			percent: t > 0 ? Math.round((c / t) * 100) : 0,
+		};
+	}, [progress]);
 
 	// Live ETA calculation
 	const [eta, setEta] = useState<string | null>(null);
+	const completedRef = useRef(completed);
+	const totalRef = useRef(total);
+	completedRef.current = completed;
+	totalRef.current = total;
+
 	useEffect(() => {
 		if (done || !startTime || completed === 0) {
 			setEta(null);
 			return;
 		}
-		const elapsed = Date.now() - startTime;
-		const avgPerItem = elapsed / completed;
-		const remaining = (total - completed) * avgPerItem;
-		setEta(formatEta(remaining));
-
-		const interval = setInterval(() => {
+		const calc = () => {
 			const elapsed = Date.now() - startTime;
-			const avgPerItem = elapsed / completed;
-			const remaining = (total - completed) * avgPerItem;
+			const avgPerItem = elapsed / completedRef.current;
+			const remaining = (totalRef.current - completedRef.current) * avgPerItem;
 			setEta(formatEta(remaining));
-		}, 2000);
+		};
+		calc();
+		const interval = setInterval(calc, 2000);
 		return () => clearInterval(interval);
-	}, [done, startTime, completed, total]);
+	}, [done, startTime, completed]);
 
 	return (
 		<div className="border-t border-[var(--admin-border)] p-3">
@@ -244,4 +253,4 @@ export function BatchProgress({
 			</div>
 		</div>
 	);
-}
+});