Add stylelint to clean code linters list

[ntwb]

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• I followed the contributing guidelines: https://github.com/github/explore/blob/main/CONTRIBUTING.md.
• This change is not self-promotion.

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• Suggesting edits to an existing topic or collection
• Curating a new topic or collection
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Editing an existing topic or collection

I'm suggesting these edits to an existing topic or collection:

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Stylelint has been around for ~10 years and is a mighty CSS linter that helps you avoid errors and enforce conventions.

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[Copilot]

Pull request overview

This PR adds stylelint to the clean code linters collection. Stylelint is a mature CSS linter that helps developers avoid errors and enforce style conventions in CSS, SCSS, and other style files.

• Adds stylelint/stylelint to the items list

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