chore: map npm package links to npmx.dev (#134)

Update README badge links from `npmjs.org` to `npmx.dev`.

- `[npm-url]` and `[download-url]` now point to
`npmx.dev/package/compressing`
- Registry URL in code example left unchanged (actual API endpoint)

<!-- START COPILOT CODING AGENT TIPS -->
---

🔒 GitHub Advanced Security automatically protects Copilot coding agent
pull requests. You can protect all pull requests by enabling Advanced
Security for your repositories. [Learn more about Advanced
Security.](https://gh.io/cca-advanced-security)

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: fengmk2 <156269+fengmk2@users.noreply.github.com>

Author: Copilot

README.md

@@ -8,11 +8,11 @@
 ![CodeRabbit Pull Request Reviews](https://img.shields.io/coderabbit/prs/github/node-modules/compressing)
 
 [npm-image]: https://img.shields.io/npm/v/compressing.svg?style=flat-square
-[npm-url]: https://npmjs.org/package/compressing
+[npm-url]: https://npmx.dev/package/compressing
 [codecov-image]: https://codecov.io/gh/node-modules/compressing/branch/master/graph/badge.svg
 [codecov-url]: https://codecov.io/gh/node-modules/compressing
 [download-image]: https://img.shields.io/npm/dm/compressing.svg?style=flat-square
-[download-url]: https://npmjs.org/package/compressing
+[download-url]: https://npmx.dev/package/compressing
 
 The missing compressing and uncompressing lib for node.