Case-insenstive support

[antfu]

Describe the bug

When deploying to Netlify, it will redirect the URLs to the lowercase version (which is forced and no way to opt-out). When we serving docs that contain uppercases, the SSG content will be displayed correctly, and after JS loading finished, the whole page will be completely white out.

To Reproduce

Example demo: https://5ff76cdd71e66e000a4ef7f0--vueuse.netlify.app/core/useMouse/

Expected behavior

Resolve the lean.js hash case-insensitively.

System Info

• vitepress version: 0.10.7
• vite version: 2.0.0-beta.10
• Node version: v14.15.3
• OS version: macOS v11.1

Additional context

With #203: https://vitepress--vueuse.netlify.app/core/useMouse/