Fix Storybook 10 build command compatibility

[Copilot]

• Understand the task - explain why packages were added
• Investigated recent commits and package changes
• Found the Dependabot PR Bump tar and storybook in /docs #2965 that upgraded Storybook
• Analyzed the changes in docs/package.json
• Provide comprehensive explanation to the user

Original prompt

Fix the failing GitHub Actions workflow Deploy preview / Build
Analyze the workflow logs, identify the root cause of the failure, and implement a fix.
Job ID: 61310416475
Job URL: https://github.com/primer/css/actions/runs/21298595492/job/61310416475

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[changeset-bot]

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Latest commit: d34140a

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