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/1958/worldcup.stadiums.json

@@ -0,0 +1,52 @@
+{
+  "stadiums": [
+    {
+      "name": "Malmö Stadion",
+      "city": "Malmö"
+    },
+    {
+      "name": "Örjans Vall",
+      "city": "Halmstad"
+    },
+    {
+      "name": "Olympiastadion",
+      "city": "Helsingborg"
+    },
+    {
+      "name": "Idrottsparken",
+      "city": "Norrköping"
+    },
+    {
+      "name": "Arosvallen",
+      "city": "Västerås"
+    },
+    {
+      "name": "Eyravallen",
+      "city": "Örebro"
+    },
+    {
+      "name": "Tunavallen",
+      "city": "Eskilstuna"
+    },
+    {
+      "name": "Råsunda Stadium",
+      "city": "Solna"
+    },
+    {
+      "name": "Jernvallen",
+      "city": "Sandviken"
+    },
+    {
+      "name": "Rimnersvallen",
+      "city": "Uddevalla"
+    },
+    {
+      "name": "Ullevi",
+      "city": "Gothenburg"
+    },
+    {
+      "name": "Ryavallen",
+      "city": "Borås"
+    }
+  ]
+}