feat: more-standard settings for hiding the navigation bar

[robsimmons]

Makes several changes:

• Moves the state control for hiding the navbar to jotai atoms, which is more idiomatic than contexts for this project
• Generalizes the state control for hiding the navbar so that it will work for permanently dismissing comparator warnings as well
• If we don't have hideNavbar set to true, the setting totally removes itself from local storage (the existing setting didn't make it possible for users to delete their stored information in the UI, which wasn't great)
• Updates some formatting, lean4web has added prettier since these features were added on our fork
• Removes the ?hide=true query-param behavior. This was causing a localstorage write whenever anyone visited the site, which is almost certainly wrong, and I wasn't able to wrap my head around the correct override hierarchy of toggles versus localstorage versus queryparams

The new logic is almost entirely settings-atoms.ts, and NavBar.tsx is almost entirely reformatting.