Mobile polish (round 1): text-first hero, fixed nav…

Details

- Hero on phones is now text-first (eyebrow/title/lede/CTAs above the
  fold); portrait moved below, smaller and centered; drop the forced
  full-viewport min-height that pushed the intro down.
- Mobile nav: keep the close (X) pinned top-right when the menu is open
  instead of dropping below the links; bump the toggle to 44px and add
  link tap padding.
- Add footer bottom padding so links aren't hidden under the floating
  theme/weather toggle dock.

Files changed (1)