fix: avoid browser esm test dist race

Rely on the pre-test build output instead of rebuilding package dist inside a parallel Vitest worker.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: chillenious

tests/browser-esm-private-child-elements.test.ts

@@ -1,9 +1,7 @@
-import { execFileSync } from 'node:child_process';
 import { readFile } from 'node:fs/promises';
 import { dirname, join } from 'node:path';
 import { pathToFileURL } from 'node:url';
 import { globSync } from 'glob';
-import { beforeAll } from 'vitest';
 
 type PrivateChildCase = {
   slug: string;
@@ -61,15 +59,6 @@ async function importBuiltView(path: string): Promise<void> {
 describe('browser ESM private child custom elements', () => {
   const root = process.cwd();
 
-  beforeAll(() => {
-    for (const { slug } of cases) {
-      execFileSync('bun', ['run', '--cwd', `packages/elements-react/${slug}`, 'build'], {
-        cwd: root,
-        stdio: 'pipe',
-      });
-    }
-  }, 60_000);
-
   test('shared browser build preserves package-owned private child registration', async () => {
     const browserConfig = await readFile(
       join(root, 'tools/vite/element-browser.config.ts'),