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.Content/PeopleDefs.cs

@@ -120,6 +120,18 @@ public sealed class SkillDef : Def
     public IReadOnlyList<AgeMeanPoint> AgeMeans { get; init; } = [];
 
     public IReadOnlyList<BodySkillLimit> BodyLimits { get; init; } = [];
+
+    /// <summary>Everyone has this: body, speech, the floor under a profession.</summary>
+    public bool Always { get; init; }
+
+    /// <summary>Adult extras: cook, nurse, secretary. Not rolled for pupils.</summary>
+    public bool Work { get; init; }
+
+    /// <summary>
+    /// Probability that an adult also has this, on top of the native language. 0 means never
+    /// by chance — pupils still get it when a subject of their year points here.
+    /// </summary>
+    public float AdultChance { get; init; }
 }
 
 public sealed class SubjectSkillShare
@@ -338,6 +350,34 @@ public sealed class NameSetDef : Def
 
     public string DefaultSurnameDeclension { get; init; } = NameGrammar.Ov;
 
+    /// <summary>
+    /// Languages this set can speak natively. Slavic names cover Russian, Belarusian and
+    /// Ukrainian; the school picks one at create. Singular <see cref="NativeLanguage"/> is still
+    /// accepted in JSONC for a one-language pack.
+    /// </summary>
+    public IReadOnlyList<string> NativeLanguages { get; init; } = [];
+
+    /// <summary>One-language form. Folded into <see cref="Spoken"/> when the list is empty.</summary>
+    public string? NativeLanguage { get; init; }
+
+    public IReadOnlyList<string> Spoken =>
+        NativeLanguages.Count > 0
+            ? NativeLanguages
+            : string.IsNullOrWhiteSpace(NativeLanguage) ? [] : [NativeLanguage];
+
+    /// <summary>
+    /// Chance each other language in <see cref="Spoken"/> is present at a low level — a Russian
+    /// speaker who understands Belarusian. 0 leaves relatives off the card.
+    /// </summary>
+    public float RelatedLanguageChance { get; init; }
+
+    public float RelatedLanguageMean { get; init; } = 22f;
+
+    public float RelatedLanguageStdDev { get; init; } = 8f;
+
+    /// <summary>Cap so a related roll cannot look like a native speaker.</summary>
+    public int RelatedLanguageMax { get; init; } = 40;
+
     public IReadOnlyList<GivenNameEntry> MaleGiven { get; init; } = [];
 
     public IReadOnlyList<GivenNameEntry> FemaleGiven { get; init; } = [];