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/program.ts

@@ -16,14 +16,14 @@
 
 import { program } from 'commander';
 
-import { createServer } from './index';
-import { ServerList } from './server';
+import { createServer } from './index.js';
+import { ServerList } from './server.js';
 
-import { startHttpTransport, startStdioTransport } from './transport';
+import { startHttpTransport, startStdioTransport } from './transport.js';
 
-import { resolveConfig } from './config';
+import { resolveConfig } from './config.js';
 
-const packageJSON = require('../package.json');
+import packageJSON from '../package.json' with { type: 'json' };
 
 program
     .version('Version ' + packageJSON.version)