feat(site): add polished animations to landing page

[manthan787]

Summary

• Add 9 polished animations to the landing page: character-level hero text reveal with stagger, gradient shimmer on accent text, infinite marquee for stack strip, mouse-tracking spotlight on capability cards, scroll-linked progress line for How It Works flow, terminal typing effect, counter animations on step numbers, and magnetic button effect
• Refactor initAnimations() into modular functions for each animation
• Full prefers-reduced-motion accessibility support (CSS + JS early return)

Test plan

• Open docs/index.html in browser — hero title animates character-by-character on load
• Shimmer sweeps across accent text after ~2s
• Stack strip scrolls horizontally, pauses on hover, edge fades visible
• Scroll to capabilities — purple spotlight follows mouse on cards
• Scroll to How It Works — progress line fills as you scroll, step numbers count up
• Scroll to spotlight — terminal lines appear sequentially
• Hover primary buttons — magnetic pull + elastic spring-back
• Test with prefers-reduced-motion: reduce in devtools — all animations disabled
• Test mobile responsive — marquee works, progress line hidden, no broken layouts

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