fix: resolve ES modules compatibility in E2E test files

- Replace __dirname with import.meta.url pattern for ES modules compatibility
- Add fileURLToPath imports to all E2E test files
- Fix duplicate require statements in setup-verification.spec.ts
- Update playwright.config.ts to use relative path instead of __dirname

This fixes the 'ReferenceError: __dirname is not defined in ES module scope' error
when running Playwright tests in the ES modules environment.

node_modules/scheduler/README.md

@@ -0,0 +1,9 @@
+# `scheduler`
+
+This is a package for cooperative scheduling in a browser environment. It is currently used internally by React, but we plan to make it more generic.
+
+The public API for this package is not yet finalized.
+
+### Thanks
+
+The React team thanks [Anton Podviaznikov](https://podviaznikov.com/) for donating the `scheduler` package name.