feat(shiki): use wasm engine

[avivkeller]

Using the WASM generator rather than the JS one results in ~50% cheaper runs.

[Copilot]

Pull Request Overview

This PR switches Shiki’s syntax highlighter from the JavaScript regex engine to the faster Oniguruma WASM engine, reducing execution cost by ~50%.

• Replaced createJavaScriptRegexEngine import and usage with createOnigurumaEngine
• Updated highlighter initialization to use dynamic WASM import

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 66.57%. Comparing base (b3e2fbd) to head (3f70af7).
Report is 2 commits behind head on main.

✅ All tests successful. No failed tests found.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #320       +/-   ##
===========================================
+ Coverage   51.15%   66.57%   +15.42%     
===========================================
  Files          81       81               
  Lines        6956     6956               
  Branches      306      339       +33     
===========================================
+ Hits         3558     4631     +1073     
+ Misses       3395     2322     -1073     
  Partials        3        3               

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[avivkeller]

Requesting fast-track so I can improve other aspects of Shiki's speed without conflicts.

Edit: Nevermind, the improvement I had in mind did not improve speeds.