Enhance staffing management in school simulation by introducing API endpoints for hiring staff and assigning subjects. Implement payroll cap validation to ensure hiring and subject assignments do not exceed the allocated budget. Update the simulation options to include a monthly payroll cap and revise related classes to support new staffing functionalities. Enhance documentation to reflect these changes and update tests to validate the new features.

src/HSchool.People/Roster.cs

@@ -40,6 +40,12 @@ public sealed record Person
 
     public required IReadOnlyDictionary<string, float> Needs { get; init; }
 
+    /// <summary>SubjectDef names this staff member is assigned. Empty for everyone else.</summary>
+    public IReadOnlyList<string> Subjects { get; init; } = [];
+
+    /// <summary>Hourly rate frozen at hire. Null until the person is staff.</summary>
+    public float? HourlyWageAsk { get; init; }
+
     public int AgeOn(DateTime asOf) => SchoolYears.AgeYears(BirthDate, asOf);
 }