feat(landing): richer scroll motion + animated CTA buttons

[SheinRG]

Make the marketing page feel alive on scroll and reward hover on the primary CTAs.

• Reveals now lift further from below through a soft blur, with an opt-in data-reveal-stagger that cascades a container's children (value-prop cards enter one after another).
• Hero headline gains an entrance and the hero copy drifts with a gentle scroll parallax; add a slim lime scroll-progress bar.
• Rebuild both CTAs (hero + final) with a bouncy shrink and a seamless text swap to "Go for it" on hover, disabled under reduced motion.
• Drop the magnetic-button behaviour and its now-dead controller code.

What changed and why

Screenshots

Checklist

• npm run lint, npm run typecheck, npm run test, and npm run build pass locally
• New/changed behavior is covered by a test
• Loading, empty, and error states handled for any new async view