This PR introduces Keystatic to let us edit twenty.com's content with a
CMS. For now, we'll focus on creating release notes through Keystatic as
it uses quite simple Markdown. Other types of content will need some
refactoring to work with Keystatic.
https://github.com/user-attachments/assets/e9f85bbf-daff-4b41-bc97-d1baf63758b2
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Co-authored-by: Félix Malfait <felix@twenty.com>