feat(site): calmer type, fitted hero, more motion - #25

Summary

• Hero is two columns on desktop and fits one screen; stacks on phones without cutting the window off.
• Smaller, calmer type scale (hero 30–48px, headings 28–48px, body 15–17px).
• Pinned tour and horizontal "Anywhere" sections are sized from the viewport height and start under the nav.
• More motion: drifting aurora, shimmer eyebrow, rotating beam borders, scroll progress bar, nav state, pointer spotlight, hero window turn, fading floats, bento parallax, logo rings. All off under prefers-reduced-motion.
• Fixes a sideways overflow from the background glow.

Test plan

• Claude in Chrome at 1536×730: scrolled the whole page with the wheel
• Phone width 390×720 (iframe): every section, no horizontal overflow