feat: rebuild landing page from new Figma design (node 9505:537)

Complete redesign with 9 sections matching the updated 1920px layout:
- Header: sticky nav with globe/language toggle and Download CTA
- Hero: warm beige bg, iPhone mockup, "A Modern Way to Stay Connected"
- WhyTalkPro: 2x2 card grid with SVG icons and illustration
- CoreSystem: halftone bg, 6-card feature grid with 3D icons
- Experience: 3 vertical screenshot cards with exact Figma clip positions
- UseCases: split layout with 4 orange-header rows
- Trust: 4-column reliability features with sprite clipping and SVG dividers
- AppPreview: interactive phone carousel with prev/next fade transition
- DownloadCTA: polka-dot bg, TalkPro logo script, store badges
- Footer: logo, description, store badges, link columns

All 35 Figma assets downloaded locally (SVGs correctly named .svg).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

public/assets/why-underline.svg

@@ -0,0 +1,3 @@
+<svg preserveAspectRatio="none" width="100%" height="100%" overflow="visible" style="display: block;" viewBox="0 0 295.5 1" fill="none" xmlns="http://www.w3.org/2000/svg">
+<path id="Vector 15" d="M0 0.5H295.5" stroke="var(--stroke-0, #F08458)"/>
+</svg>