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.Schedule.Tests/TimetablePlannerTests.cs

@@ -146,6 +146,50 @@ public class TimetablePlannerTests
         }
     }
 
+    /// <summary>
+    /// The four bans alone allowed a legal but unusable week. Taking the first free slot day by
+    /// day gave a full school 77 lessons on Monday and 16 on Friday, with three foreign-language
+    /// lessons back to back. These are the numbers a timetable is judged by, so they are asserted.
+    /// </summary>
+    [Fact]
+    public void AWeek_IsSpreadAcrossDaysAndSubjectsDoNotRunInBlocks()
+    {
+        var catalog = Fixtures.Catalog();
+        var map = Fixtures.ClassroomsAndGym(11);
+        var classes = Enumerable.Range(0, 11).Select(index => Fixtures.Class(index, index + 1, 16)).ToArray();
+        var teachers = catalog.Subjects.Values
+            .Where(subject => !subject.Abstract)
+            .SelectMany(subject => Enumerable
+                .Range(0, 3)
+                .Select(copy => Fixtures.Teacher($"t{subject.DefName}{copy}", subject.DefName)))
+            .ToArray();
+
+        var table = TimetablePlanner.Build(catalog, map, classes, teachers);
+
+        var perDay = Enumerable.Range(0, 5).Select(day => table.Lessons.Count(lesson => lesson.Day == day)).ToArray();
+        Assert.All(perDay, count => Assert.True(count > 0, $"a school day is empty: {string.Join("/", perDay)}"));
+        Assert.True(
+            perDay.Max() <= perDay.Min() * 1.5,
+            $"the week is lopsided: {string.Join("/", perDay)}");
+
+        // Spread as evenly as the curriculum allows, not "never twice a day": primary school is
+        // twenty hours over five days, so four a day is the best that exists.
+        foreach (var group in table.Lessons.GroupBy(lesson => (lesson.ClassId, lesson.Subject)))
+        {
+            var bySubjectDay = Enumerable
+                .Range(0, 5)
+                .Select(day => group.Count(lesson => lesson.Day == day))
+                .ToArray();
+
+            // Two, not one: the day order is a preference, and a busy room or teacher can still
+            // push an hour onto a day that already has the subject. Before the fix the same
+            // measurement read 5/5/5/0/0.
+            Assert.True(
+                bySubjectDay.Max() - bySubjectDay.Min() <= 2,
+                $"{group.Key.ClassId} has {group.Key.Subject} bunched into days: {string.Join("/", bySubjectDay)}");
+        }
+    }
+
     private static string Snapshot(Timetable table) =>
         string.Join(
             '\n',