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/1962/worldcup.stadiums.json

@@ -0,0 +1,20 @@
+{
+  "stadiums": [
+    {
+      "name": "Estadio Carlos Dittborn",
+      "city": "Arica"
+    },
+    {
+      "name": "Estadio El Teniente",
+      "city": "Rancagua"
+    },
+    {
+      "name": "Estadio Sausalito",
+      "city": "Viña del Mar"
+    },
+    {
+      "name": "Estadio Nacional",
+      "city": "Santiago"
+    }
+  ]
+}