Create Public Notes

[xeust]

2 PRs:

Backend:

• have an is_public field which can be modified via an api route (when someone clicks the lock in the frontend).
• serve a different version of the note

Frontend:

• different version of the note
• route substitution logic for links / backlinks needs to include the /public route
• Move backlinks / links sidebar to the left, remove left sidebar entirely
• Include 'Install on Deta' button somewhere in the note (likely the bottom bar)