Feature: Add right/left n/p keyboard navigation to all Python docs

Describe the enhancement or feature you would like

Right now the accessibility audit https://github.com/python/devguide/issues/1792 is blocking keyboard navigation https://github.com/python/devguide/pull/1784 not only for devguide, but across Python ecosysem https://github.com/orgs/sphinx-doc/discussions/14406 https://github.com/sphinx-doc/sphinx/pull/14408 https://github.com/readthedocs/sphinx_rtd_theme/pull/1686 https://github.com/pradyunsg/furo/discussions/932

Clearly, other projects may not have the resources to access the risk of hurting sensitive auditory, so all maintainers just don't take it - and while Sphinx comes with keyboard shortcuts, no project across Pyto ecosystem enables it.

Now that there is a chance to do accessibility study, please make sure that both arrow keys and vim `style n/p keys are evaluated for usage, with official "documentation accessibility" chapter, that could be easily referenced for other projects to follow.

Thanks for your time, folks.

Describe alternatives you have considered

No response

Additional context

No response

リンクされているアクセシビリティ監査、devguide のナビゲーションに関するプルリクエスト、Sphinx エコシステムでの議論をまず確認し、指摘されているリスクと既存のアプローチを理解します。公式ドキュメントのアクセシビリティ章の範囲と、Python ドキュメントプロジェクト全体で矢印キーによるナビゲーションおよび vim スタイルの n/p ナビゲーションをどのように評価すべきかを定義します。完了時には、他のメンテナーが参照できるガイダンスを提供できるようにします。