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/1978/worldcup.stadiums.json

@@ -0,0 +1,48 @@
+{
+  "stadiums": [
+    {
+      "name": "River Plate Stadium",
+      "city": "Buenos Aires"
+    },
+    {
+      "name": "Estadio José María Minella",
+      "city": "Mar del Plata"
+    },
+    {
+      "name": "Estadio Monumental",
+      "city": "Buenos Aires"
+    },
+    {
+      "name": "Estadio Gigante de Arroyito",
+      "city": "Rosario"
+    },
+    {
+      "name": "Estadio Chateau Carreras",
+      "city": "Córdoba"
+    },
+    {
+      "name": "Estadio Olímpico Chateau Carreras",
+      "city": "Córdoba"
+    },
+    {
+      "name": "Estadio José Amalfitani",
+      "city": "Buenos Aires"
+    },
+    {
+      "name": "Estadio José Maria Minella",
+      "city": "Mar del Plata"
+    },
+    {
+      "name": "Chateau Carreras",
+      "city": "Córdoba"
+    },
+    {
+      "name": "Estadio Ciudad de Mendoza",
+      "city": "Mendoza"
+    },
+    {
+      "name": "Estadio Malvinas Argentinas",
+      "city": "Mendoza"
+    }
+  ]
+}