Landing navbar: Features and Updates menus

The marketing navbar now helps you jump around the homepage without scrolling blindly. The Features menu links straight to AI journaling, performance charts, calendar, performance tracking, and data import. Updates opens the changelog and our YouTube channel. Pricing summarizes Basic and Plus plans with a link to the pricing section.

On mobile, the menu uses accordions for theme and language, locks page scroll while open, and smooth-scrolls to in-page anchors when you pick a section.