refactor: replace hardcoded hex colors with theme tokens, move data/ to root

- Add --color-green-mid token (#4a7a55) to @theme for dimmer stat values
- Replace all text-[#hex]/bg-[#hex] arbitrary values with named tokens:
  text-green, text-green-light, text-green-sec, text-green-muted,
  text-green-dark, text-green-mid, text-text, bg-card, bg-bg, border-border
- Replace rgba(34,197,94,X) inline styles with bg-green/X opacity modifiers
- Convert single-prop style={{ borderColor/background }} to className
- Fix SVG stroke="#dff5e8" → stroke="currentColor"
- Use CSS variables in globals.css base styles (background-color, color)
- Move app/data/wikipedia/ → data/ (project root, not inside Next.js app dir)
- Update Dockerfile, seed.ts, scrape-wikipedia.ts paths accordingly
- Remove unused app/data/world_cup.csv

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

app/not-found.tsx

@@ -9,15 +9,15 @@ export default function NotFound() {
       <div
         className="pitch-grid glass-card-hero rounded-2xl px-12 py-16 w-full max-w-lg"
       >
-        <div className="font-['Bebas_Neue'] text-[120px] text-[#22c55e] leading-none">
+        <div className="font-['Bebas_Neue'] text-[120px] text-green leading-none">
           404
         </div>
-        <p className="text-[#6abf7a] text-lg mt-2 mb-8">
+        <p className="text-green-sec text-lg mt-2 mb-8">
           This page doesn&apos;t exist.
         </p>
         <Link
           href="/"
-          className="inline-block font-['Bebas_Neue'] text-xl tracking-[0.1em] text-[#040d08] bg-[#22c55e] px-8 py-3 rounded-xl hover:bg-[#4ade80] transition-colors"
+          className="inline-block font-['Bebas_Neue'] text-xl tracking-[0.1em] text-bg bg-green px-8 py-3 rounded-xl hover:bg-green-light transition-colors"
         >
           Back to Home
         </Link>