refactor: rename data/openfootball → data/wikipedia, drop data/kaggle

Move world_cup.csv to app/data/ directly (the only remaining Kaggle file
used by seed.ts for tournament metadata). Delete the rest of the Kaggle CSVs.
Update path constants in scrape-wikipedia.ts and seed.ts accordingly.

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

app/data/wikipedia/1998/worldcup.stadiums.json

@@ -0,0 +1,48 @@
+{
+  "stadiums": [
+    {
+      "name": "Stade Vélodrome",
+      "city": "Marseille"
+    },
+    {
+      "name": "Parc des Princes",
+      "city": "Paris"
+    },
+    {
+      "name": "Stade Félix-Bollaert",
+      "city": "Lens"
+    },
+    {
+      "name": "Stade de France",
+      "city": "Saint-Denis"
+    },
+    {
+      "name": "Stade de la Mosson",
+      "city": "Montpellier"
+    },
+    {
+      "name": "Stade de Toulouse",
+      "city": "Toulouse"
+    },
+    {
+      "name": "Parc Lescure",
+      "city": "Bordeaux"
+    },
+    {
+      "name": "Stade Geoffroy-Guichard",
+      "city": "Saint-Étienne"
+    },
+    {
+      "name": "Stade de la Beaujoire",
+      "city": "Nantes"
+    },
+    {
+      "name": "Stade de Gerland",
+      "city": "Lyon"
+    },
+    {
+      "name": "Stade Gerland",
+      "city": "Lyon"
+    }
+  ]
+}