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/tool.ts

@@ -14,11 +14,11 @@
  * limitations under the License.
  */
 
-import type { ImageContent, TextContent } from '@modelcontextprotocol/sdk/types';
+import type { ImageContent, TextContent } from '@modelcontextprotocol/sdk/types.js';
 import type { z } from 'zod';
-import type { Context } from '../context';
+import type { Context } from '../context.js';
 import type * as playwright from 'playwright';
-import type { ToolCapability } from '../../config';
+import type { ToolCapability } from '../../config.js';
 
 export type ToolSchema<Input extends InputType> = {
   name: string;