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/2010/worldcup.stadiums.json

@@ -0,0 +1,44 @@
+{
+  "stadiums": [
+    {
+      "name": "Nelson Mandela Bay Stadium",
+      "city": "Port Elizabeth"
+    },
+    {
+      "name": "Royal Bafokeng Stadium",
+      "city": "Rustenburg"
+    },
+    {
+      "name": "Free State Stadium",
+      "city": "Bloemfontein"
+    },
+    {
+      "name": "Soccer City",
+      "city": "Johannesburg"
+    },
+    {
+      "name": "Moses Mabhida Stadium",
+      "city": "Durban"
+    },
+    {
+      "name": "Ellis Park Stadium",
+      "city": "Johannesburg"
+    },
+    {
+      "name": "Loftus Versfeld Stadium",
+      "city": "Pretoria"
+    },
+    {
+      "name": "Cape Town Stadium",
+      "city": "Cape Town"
+    },
+    {
+      "name": "Peter Mokaba Stadium",
+      "city": "Polokwane"
+    },
+    {
+      "name": "Mbombela Stadium",
+      "city": "Nelspruit"
+    }
+  ]
+}