feat(ui): rebuild landing page on a Stripe-style grid

[CodeWithEugene]

Summary

Rebuilds the home page (app/(marketing)/page.tsx) using Stripe's landing-page structure, keeping HackVillage's fonts, colour tokens and pill-button system.

• Frame: one continuous ruled column with hairline side rules and horizontal rules between sections. The navbar is now left-aligned (logo and links left, actions right), and on the landing page it lines up with the frame.
• Hero: two-tone statement heading plus a brand-blue SVG ribbon.
• Partner marquee: Salamander Tech Hub, Technetium Kenya and SkillsSync Global.
• Bento product cards: mock screens for the prize vault, 50/50 payouts, judging, Proof-of-Work, the public ledger and the organizer dashboard.
• Photo banner: "Organizers ghost winners. We fixed that."
• Interactive trust stats: the stats work as a tab menu with a sliding gradient indicator. A canvas burst shows what each stat means (100% / 50% / 1hr sweep / 0%) and follows the cursor. It auto-cycles, pauses on hover or focus, stops when a stat is clicked, and respects reduced motion.
• Audience sections: organizers (case study and accordion), builders (journey carousel and promos), hiring (showcase, features, pull quote).
• Navy open-infrastructure band: money-flow diagram, waves with stats, and three ways to take part.
• Latest posts and closing CTA: latest posts come from lib/blog, followed by a closing call to action.

The "What Is HackVillage?" copy is unchanged word for word, for SEO and answer engines. The old landing components (landing-hero, landing-about, builder-journey, trust-impact) and their CSS are removed; /how-it-works still uses the hero-action* rules, so those stay.

No escrow, payout or contract code is touched.

Notes for review

• The mock screens use sample names and figures ("Team Jua", "Wanjiku K.", "Mombasa Fintech Sprint", KES amounts). The rules they illustrate are the platform's (5% fee on top, 50/50 tranches, 30-day milestone).
• Partner logos aren't linked yet; the Technetium and SkillsSync URLs are still needed.

Test plan

• tsc --noEmit and next lint pass
• Checked in the browser at 1440px, 1920px and 375px, in light and dark mode, with no horizontal overflow
• Carousel arrows, accordion rows, stat tabs, indicator, canvas states and pointer response work in headless Chrome
• /how-it-works renders unchanged after the CSS cleanup