typst wrong syntax highlighting

[l0uisgrange]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Hey there 👋, thanks @alecthomas for this package!
The syntax highlighting for the typst language is not correct: the grammar needs to be updated. Here's a comparison with the current GitHub highlighting to demonstrate the issue visually.

Chroma	GitHub

I've not found the correct grammar as xml, but found this in json and also this one from Shiki.js if that helps.

To Reproduce

Here is the reproduction.

[Apollo3zehn]

I face a similar problem where accessed variables are highlighted incorrectly

The underscore in the variable name seems to cause problems