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.

src/HSchool.Simulation/SchoolRegistry.cs

@@ -11,6 +11,7 @@ public enum SchoolCreationError
     UnknownMod,
     InvalidCatalog,
     UnknownNameSet,
+    UnknownNativeLanguage,
 }
 
 /// <summary>Outcome of <see cref="SchoolRegistry.Create"/>: either the school or the reason there is none.</summary>