The toggle navigation menu button is not keyboard accessible

The toggle navigation menu button when present (on smaller screens) is not keyboard accessible (it can be interacted via tab navigation + enter):
![Image](https://github.com/user-attachments/assets/cccca9ae-337f-420c-9f9e-52957644c855)

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Original context for the issue: https://github.com/nodejs/api-docs-tooling/pull/285#issuecomment-2998307585