Right-to-left writing and gentle feature discovery

New

• Natural right-to-left text direction — notes in Arabic, Hebrew, Persian, Urdu, and other RTL scripts now flow the way native readers expect. Headings, paragraphs, lists, task items, and block quotes align naturally per paragraph, while code blocks and Markdown syntax stay left-to-right so structure doesn't flip.
• Preview mode tip — a one-time popover introduces preview mode when you first settle into a note, then quietly retires once you've tried it.