feat(shiki): allow custom highlighters, avoid async rehype

[avivkeller]

This'll make it possible to define a custom Shiki singleton for rehype-shiki to use (ie if you want to define your Shiki instance elsewhere).

It also makes Shiki a non-async rehype plugin

[vercel]

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Project	Deployment	Preview	Updated (UTC)
nodejs-org	Ready	Preview	Nov 2, 2025 6:13pm

[codecov]

Codecov Report

❌ Patch coverage is 82.35294% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 76.71%. Comparing base (e753dd2) to head (2949616).
⚠️ Report is 4 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
packages/rehype-shiki/src/index.mjs	0.00%	2 Missing ⚠️
packages/rehype-shiki/src/plugin.mjs	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8320      +/-   ##
==========================================
+ Coverage   76.61%   76.71%   +0.09%     
==========================================
  Files         117      118       +1     
  Lines        9751     9805      +54     
  Branches      328      335       +7     
==========================================
+ Hits         7471     7522      +51     
- Misses       2278     2281       +3     
  Partials        2        2              

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[Copilot]

Pull Request Overview

This PR refactors the rehype-shiki plugin to support an optional pre-initialized highlighter instance, transitioning from a traditional function declaration to an arrow function pattern while improving type documentation.

Key changes:

• Refactored the plugin to accept an optional highlighter parameter and use arrow function syntax
• Fixed JSDoc syntax errors by converting @param to @property for type definition fields
• Added comprehensive type definition for SyntaxHighlighter in the highlighter module

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
packages/rehype-shiki/src/plugin.mjs	Refactored to arrow function syntax and updated to accept optional highlighter parameter
packages/rehype-shiki/src/index.mjs	Fixed JSDoc syntax by converting @param to @property for HighlighterOptions fields
packages/rehype-shiki/src/highlighter.mjs	Added SyntaxHighlighter typedef and return type documentation
packages/rehype-shiki/package.json	Bumped version from 1.2.0 to 1.3.0

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[avivkeller]

Deployment works locally, cc @nodejs/web-infra

[avivkeller]

PTAL @nodejs/nodejs-website