chore: map npm package link to npmx.dev (#285)

Update README badge links to point to `npmx.dev` instead of `npmjs.org`.

- `[npm-url]`: `npmjs.org/package/bug-versions` →
`npmx.dev/package/bug-versions`
- `[download-url]`: `npmjs.org/package/bug-versions` →
`npmx.dev/package/bug-versions`

Badge image sources (`img.shields.io`) are unchanged.

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

✨ Let Copilot coding agent [set things up for
you](https://github.com/cnpm/bug-versions/issues/new?title=✨+Set+up+Copilot+instructions&body=Configure%20instructions%20for%20this%20repository%20as%20documented%20in%20%5BBest%20practices%20for%20Copilot%20coding%20agent%20in%20your%20repository%5D%28https://gh.io/copilot-coding-agent-tips%29%2E%0A%0A%3COnboard%20this%20repo%3E&assignees=copilot)
— coding agent works faster and does higher quality work when set up for
your repo.

---------

Co-authored-by: copilot-swe-agent[bot] <[email protected]>
Co-authored-by: fengmk2 <[email protected]>

Author: Copilot

README.md

@@ -8,11 +8,11 @@
 ![CodeRabbit Pull Request Reviews](https://img.shields.io/coderabbit/prs/github/cnpm/bug-versions)
 
 [npm-image]: https://img.shields.io/npm/v/bug-versions.svg?style=flat-square
-[npm-url]: https://npmjs.org/package/bug-versions
+[npm-url]: https://npmx.dev/package/bug-versions
 [snyk-image]: https://snyk.io/test/npm/bug-versions/badge.svg?style=flat-square
 [snyk-url]: https://snyk.io/test/npm/bug-versions
 [download-image]: https://img.shields.io/npm/dm/bug-versions.svg?style=flat-square
-[download-url]: https://npmjs.org/package/bug-versions
+[download-url]: https://npmx.dev/package/bug-versions
 
 collect all bug versions on npm package.