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

src/tools/utils.ts

@@ -15,7 +15,7 @@
  */
 
 import type * as playwright from 'playwright';
-import type { Context } from '../context';
+import type { Context } from '../context.js';
 
 export async function waitForCompletion<R>(context: Context, page: playwright.Page, callback: () => Promise<R>): Promise<R> {
   const requests = new Set<playwright.Request>();