perf(studio): speed up nitro scan and stop the cleanup panel freezing

src/lib/services/nitro-cleanup.ts

@@ -217,14 +217,21 @@ interface DirectoryRead {
 	lastModified: number;
 }
 
+/**
+ * How many `stat` calls run in parallel while reading an asset directory.
+ * Directories can hold hundreds of thousands of files; serial `stat`ing them
+ * is the single biggest cost of the scan, so the work is spread over a pool.
+ */
+const DIR_STAT_CONCURRENCY = 32;
+
 async function readAssetDir(
 	dir: string,
 	regex: RegExp,
 ): Promise<DirectoryRead[]> {
 	const names = await fs.readdir(dir).catch(() => [] as string[]);
 	const entries: DirectoryRead[] = [];
-	for (const name of names) {
+	await runPool(names, DIR_STAT_CONCURRENCY, async (name) => {
-		if (!regex.test(name)) continue;
+		if (!regex.test(name)) return;
 		let size = 0;
 		let mtimeMs = 0;
 		try {
@@ -240,7 +247,7 @@ async function readAssetDir(
 			size,
 			lastModified: mtimeMs,
 		});
-	}
+	});
 	return entries;
 }
 
@@ -321,7 +328,7 @@ export async function scanFakeBrokenNitros(): Promise<NitroCleanupScan> {
 	const fake: NitroCleanupEntry[] = [];
 	const broken: NitroCleanupEntry[] = [];
 
-	await runPool(entries, 8, async (entry) => {
+	await runPool(entries, 16, async (entry) => {
 		// A .nitro that no DB item maps to is a leftover / fake bundle.
 		if (!validStems.has(entry.base.toLowerCase())) {
 			fake.push(entry);