Count-Up Stats Bento

Build a "Count-Up Stats Bento" React component.

CONCEPT: A case-study results section laid out as a bento: one big headline metric and three supporting stats. Numbers animate from zero with a spring when visible.

LAYOUT & CONTENT:
- Large tile: '+212%' organic signups with a small caption and an SVG hand-drawn terracotta underline.
- Three small tiles: '4.8s → 0.9s' load time, '38' pages shipped, '1' person on the client side.
- Tile borders 1px charcoal, generous padding, mono captions.

INTERACTIONS & MOTION:
- Use useInView(ref, { once: true }) and animate(motionValue, target, { type: 'spring', stiffness: 60, damping: 20 }) rendering rounded values.
- Underline path draws with pathLength 0 → 1 after the number finishes (delay 0.4s).
- Tiles fade-up with stagger 80ms.

DESIGN SYSTEM (non-negotiable):
- Palette: paper background #FAF9F6, deep charcoal #121212 for text and 1px borders, ONE warm accent: cobalt #1D4ED8 or terracotta #D9534F. Secondary surface #F2EFE8.
- Typography: Swiss / editorial. A tight grotesk for UI (Instrument Sans, Inter Tight or similar) with negative tracking on display sizes; an italic serif (Instrument Serif) used sparingly for one emphasized word.
- NO dark-mode neon, NO glow, NO glassmorphism, NO backdrop blur, NO purple-to-blue gradients, NO emoji icons. Solid fills, hairline rules, honest shadows (hard offset or none).
- Motion: Framer Motion with spring physics (type: "spring", stiffness 300-500, damping 20-35). Animate transform and opacity only. Respect prefers-reduced-motion via useReducedMotion().
- Icons: lucide-react, 1.5px stroke.
- Accessibility: real <button>/<a>/<label> elements, visible focus ring (2px cobalt, 3px offset), keyboard operable, aria attributes where state changes.

OUTPUT: one self-contained React component file (Tailwind CSS v4 utility classes, framer-motion, lucide-react), no external images, default export, ready to paste into a Next.js App Router page with "use client".