Mobile traffic was breaking on narrow viewports because the header nav
overflowed and several pages used desktop-only spacing. This adds a
shared phone breakpoint, a hamburger menu, and scroll-to-top on route
changes so footer and menu navigation always land at the top of the page.
- Add --page-gutter and max-width 639px rules in base.css
- AppHeader: hamburger panel on small screens; flat account links on mobile
- AppFooter: stack footer links vertically on phones
- Home, compose, edit order, orders, auth, and legal pages: tighter gutters
and responsive layout (orders card actions stack; home grids single-column)
- Router scrollBehavior: scroll to top on navigation; restore on browser back
- Tests: AppHeader menu toggle, Router scrollBehavior, mobile Playwright checks
Admin page is intentionally unchanged.
Co-authored-by: Cursor <cursoragent@cursor.com>