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>

data/2002/worldcup.stadiums.json

@@ -0,0 +1,116 @@
+{
+  "stadiums": [
+    {
+      "name": "Jeju World Cup Stadium",
+      "city": "Seogwipo"
+    },
+    {
+      "name": "Big Swan Stadium",
+      "city": "Niigata"
+    },
+    {
+      "name": "Big Eye Stadium",
+      "city": "Ōita"
+    },
+    {
+      "name": "Suwon World Cup Stadium",
+      "city": "Suwon"
+    },
+    {
+      "name": "Jeonju World Cup Stadium",
+      "city": "Jeonju"
+    },
+    {
+      "name": "Kobe Wing Stadium",
+      "city": "Kobe"
+    },
+    {
+      "name": "Miyagi Stadium",
+      "city": "Rifu"
+    },
+    {
+      "name": "Daejeon World Cup Stadium",
+      "city": "Daejeon"
+    },
+    {
+      "name": "Stadium Ecopa",
+      "city": "Fukuroi"
+    },
+    {
+      "name": "Munsu Cup Stadium",
+      "city": "Ulsan"
+    },
+    {
+      "name": "Gwangju World Cup Stadium",
+      "city": "Gwangju"
+    },
+    {
+      "name": "Nagai Stadium",
+      "city": "Osaka"
+    },
+    {
+      "name": "Seoul World Cup Stadium",
+      "city": "Seoul"
+    },
+    {
+      "name": "Saitama Stadium",
+      "city": "Saitama"
+    },
+    {
+      "name": "Daegu World Cup Stadium",
+      "city": "Daegu"
+    },
+    {
+      "name": "International Stadium",
+      "city": "Yokohama"
+    },
+    {
+      "name": "Busan Asiad Main Stadium",
+      "city": "Busan"
+    },
+    {
+      "name": "Incheon World Cup Stadium",
+      "city": "Incheon"
+    },
+    {
+      "name": "Munsu Football Stadium",
+      "city": "Ulsan"
+    },
+    {
+      "name": "Niigata Stadium",
+      "city": "Niigata"
+    },
+    {
+      "name": "Sapporo Dome",
+      "city": "Sapporo"
+    },
+    {
+      "name": "Kashima Soccer Stadium",
+      "city": "Ibaraki"
+    },
+    {
+      "name": "Ecopa Stadium",
+      "city": "Shizuoka"
+    },
+    {
+      "name": "International Stadium Yokohama",
+      "city": "Yokohama"
+    },
+    {
+      "name": "Wing Stadium",
+      "city": "Kobe"
+    },
+    {
+      "name": "Niigata Big Swan Stadium",
+      "city": "Niigata"
+    },
+    {
+      "name": "Ōita Big Eye Stadium",
+      "city": "Ōita"
+    },
+    {
+      "name": "Shizuoka Ecopa Stadium",
+      "city": "Fukuroi, Shizuoka"
+    }
+  ]
+}