Explore changing the syntax highlighter engine to shiki

[wmitsuda]

I stumbled upon this accidentally while reading vite 5.2 release notes and seeing this shiki thing:

https://twitter.com/vite_js/status/1770455259069968837

it looks more well maintained than the current [problematic] solution we use for syntax highlighting, but needs to be tested.

https://github.com/shikijs/shiki