tanstack start authentication docs broken

<img width="726" height="406" alt="Image" src="https://github.com/user-attachments/assets/9713f415-7c7e-4fb9-a4d2-d0e22ef9c42a" />

https://tanstack.com/start/latest/docs/framework/react/guide/authentication#3-authentication-context

This doc so many code blocks has no content.