feat: add support for Markdown Front Matter parsing

[lumirlumir]

Prerequisites checklist

• I have read the contributing guidelines.

What is the purpose of this pull request?

Hello,

I've added support for Markdown Front Matter parsing in code-explorer!

This feature leverages the newly introduced Front Matter parsing capability in @eslint/markdown@6.4.0. (eslint/markdown#328)

code-explorer now supports parsing Front Matter in both yaml and toml formats.

• yaml

• toml

• options

What changes did you make? (Give an overview)

I've added markdownFrontmatter options to properly parse both yaml and toml front matter.

I've also introduced an Off option, which is interpreted as the boolean false.

Related Issues

eslint/markdown#328

Is there anything you'd like reviewers to focus on?

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[nzakas]

This is looking good. Can you please check the CI failures?

[Copilot]

Pull Request Overview

This pull request adds support for Markdown Front Matter parsing in code-explorer by introducing a new front matter option that supports "yaml" and "toml" formats as well as an "off" setting.

• Added a new constant array for front matter options in src/lib/const.ts
• Extended option types in src/hooks/use-explorer.ts and enabled corresponding parsing in src/hooks/use-ast.ts
• Updated the options component in src/components/options.tsx to include a front matter selection dropdown

Reviewed Changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated no comments.

File	Description
src/lib/const.ts	Introduced markdownFrontmatters constant and updated defaultMarkdownOptions
src/hooks/use-explorer.ts	Added MarkdownFrontmatter type
src/hooks/use-ast.ts	Updated AST parsing to use front matter setting
src/components/options.tsx	Added LabeledSelect for markdownFrontmatter

Files not reviewed (1)

• package.json: Language not supported

Comments suppressed due to low confidence (1)

src/lib/const.ts:193

• [nitpick] The constant name 'markdownFrontmatters' is inconsistent with the singular option property 'markdownFrontmatter' used elsewhere. Consider renaming it (e.g., 'markdownFrontmatterOptions') for improved clarity.

export const markdownFrontmatters = [

[nzakas]

LGTM. Thanks!