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/1966/worldcup.stadiums.json

@@ -0,0 +1,36 @@
+{
+  "stadiums": [
+    {
+      "name": "Wembley Stadium",
+      "city": "London"
+    },
+    {
+      "name": "Hillsborough Stadium",
+      "city": "Sheffield"
+    },
+    {
+      "name": "Roker Park",
+      "city": "Sunderland"
+    },
+    {
+      "name": "Goodison Park",
+      "city": "Liverpool"
+    },
+    {
+      "name": "White City Stadium",
+      "city": "London"
+    },
+    {
+      "name": "Villa Park",
+      "city": "Birmingham"
+    },
+    {
+      "name": "Old Trafford",
+      "city": "Manchester"
+    },
+    {
+      "name": "Ayresome Park",
+      "city": "Middlesbrough"
+    }
+  ]
+}