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/server.ts

@@ -18,10 +18,10 @@ import { Server } from '@modelcontextprotocol/sdk/server/index.js';
 import { CallToolRequestSchema, ListToolsRequestSchema } from '@modelcontextprotocol/sdk/types.js';
 import { zodToJsonSchema } from 'zod-to-json-schema';
 
-import { Context } from './context';
+import { Context } from './context.js';
 
-import type { Tool } from './tools/tool';
-import type { Config } from '../config';
+import type { Tool } from './tools/tool.js';
+import type { Config } from '../config.js';
 
 type MCPServerOptions = {
   name: string;