Enhance school creation and staffing management with native language support

- Updated protocol documentation to include `nativeLanguages` in `nameSets` and added `nativeLanguage` to school creation options.
- Enhanced the UI for school creation to allow selection of native languages, improving user experience.
- Revised API interfaces to accommodate new native language features, ensuring proper data handling.
- Improved localization strings to support new native language functionalities in both English and Russian.
- Updated tests to validate the new native language features and ensure robust functionality in staffing scenarios.

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);
+        RosterGenerator.Generate(Catalog(), map, seed, "Slavic", AsOf, "RussianLanguage");
 
     public static string RepoRoot()
     {