[Site]: improve static files performance

### Current State

## Resources Sample

1. [https://apisix-website-static.apiseven.com/zh/assets/js/runtime~main.26c4290b.js](https://apisix-website-static.apiseven.com/zh/assets/js/runtime~main.26c4290b.js)
2. [https://apisix-website-static.apiseven.com/assets/js/runtime~main.e301679c.js](https://apisix-website-static.apiseven.com/assets/js/runtime~main.e301679c.js)

## **TODO**

1. `return"assets/js/"` → with CDN
2. `return"assets/css/` → with CDN

## Other

1. [https://askubuntu.com/questions/513046/how-to-search-strings-inside-files-like-in-windows-without-search-monkey](https://askubuntu.com/questions/513046/how-to-search-strings-inside-files-like-in-windows-without-search-monkey)

### Desired State

**Description of the change you are proposing**:

See Current State

### Would you like to fix this issue?

_No response_