chore: migrate to ESM (#303)

- [Why do I need `.js`
extension?](https://stackoverflow.com/a/77150985/6512681)
- [Why setting `rootDir` in the
`tsconfig.json`?](https://stackoverflow.com/a/58941798/6512681)
- [How to ensure that we add the `.js` extension via
ESLint](https://github.com/import-js/eslint-plugin-import/blob/main/docs/rules/extensions.md#importextensions)

Fixes https://github.com/microsoft/playwright-mcp/issues/302

index.js

@@ -15,5 +15,5 @@
  * limitations under the License.
  */
 
-const { createServer } = require('./lib/index');
-module.exports = { createServer };
+import { createServer } from './lib/index';
+export default { createServer };