test: remove the asset test temp folders after the run

tests/integration/prepare-assets.test.ts

@@ -6,7 +6,7 @@ import { execFile } from 'node:child_process';
 import { promisify } from 'node:util';
 import sharp from 'sharp';
 import { BarcodeFormat, MultiFormatWriter } from '@zxing/library';
-import { describe, expect, it } from 'vitest';
+import { afterAll, describe, expect, it } from 'vitest';
 
 // @ts-expect-error The production script is native ESM and intentionally has no TypeScript runtime wrapper.
 import { hashFile } from '../../scripts/lib/hash-file.mjs';
@@ -22,7 +22,16 @@ import { generateSocialPreview } from '../../scripts/generate-social-preview.mjs
 const execFileAsync = promisify(execFile);
 interface Candidate { id: string; fileName: string; sha256: string; }
 
-const createRoot = async (): Promise<string> => mkdtemp(join(tmpdir(), 'portfolio-assets-test-'));
+const roots: string[] = [];
+const createRoot = async (): Promise<string> => {
+  const root = await mkdtemp(join(tmpdir(), 'portfolio-assets-test-'));
+  roots.push(root);
+  return root;
+};
+
+afterAll(async () => {
+  await Promise.all(roots.splice(0).map((root) => rm(root, { recursive: true, force: true })));
+});
 
 const writeJson = async (path: string, value: unknown): Promise<void> => {
   await writeFile(path, `${JSON.stringify(value, null, 2)}\n`, 'utf8');