Revamping to matrix style

node_modules/@vercel/speed-insights/vitest.config.mts

@@ -0,0 +1,10 @@
+/// <reference types="vitest" />
+import { defineConfig } from 'vitest/config';
+
+// eslint-disable-next-line import/no-default-export -- vitest needs a default export.
+export default defineConfig({
+  test: {
+    environment: 'jsdom',
+    setupFiles: './test.setup.ts',
+  },
+});