Replace selectable name sets with a country that owns names and climate presets.

Create picks a country; climate is rolled from the school seed and stored. Old Slavic saves lift as Russia.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/HSchool.People.Tests/Fixtures.cs

@@ -96,7 +96,7 @@ internal static class Fixtures
     }
 
     public static Roster Generate(MapLayout map, int seed = SchoolSeed) =>
-        RosterGenerator.Generate(Catalog(), map, seed, "Slavic", AsOf, "RussianLanguage");
+        RosterGenerator.Generate(Catalog(), map, seed, "Russia", AsOf, "RussianLanguage");
 
     public static string RepoRoot()
     {