Update staffing management to enhance payroll and hiring functionalities

- Increased the `MonthlyPayrollCap` from 10,000 to 40,000, allowing for greater flexibility in hiring and subject assignments.
- Revised payroll calculation logic to ensure that staff members are compensated based on their actual weekly hours, with a minimum payment reflecting one full rate.
- Updated documentation to clarify the new payroll structure and its implications for hiring and subject assignments.
- Enhanced tests to validate the new payroll cap and ensure proper functionality in staffing scenarios, including the handling of uncovered subjects.
- Improved localization strings to reflect changes in staffing and payroll terminology.

tests/HSchool.Content.Tests/VanillaCoreTests.cs

@@ -44,7 +44,7 @@ public class VanillaCoreTests
         Assert.NotNull(catalog.StaffingRules);
         Assert.Equal(12, catalog.StaffingRules.PoolSize);
         Assert.Equal(20, catalog.StaffingRules.BaseWeeklyHours);
-        Assert.Equal(0.25f, catalog.StaffingRules.ExtraSubjectSurcharge);
+        Assert.Equal(36, catalog.StaffingRules.MaxWeeklyHours);
         Assert.NotNull(catalog.DayFrame);
         Assert.Equal("08:30", catalog.DayFrame.FirstLesson);
         Assert.Equal(7, catalog.DayFrame.LessonCount);