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.

src/HSchool.Server/mods/core/defs/staffing/rules.jsonc

@@ -5,7 +5,10 @@
   "parentChance": 0.35,
   "hourlyWageBase": 30,
   "hourlyWagePerSkill": 0.6,
+  // One ставка. A hired person costs this much even with no subjects, and hours beyond it are
+  // paid on top — that is what makes loading one teacher instead of hiring two cost money.
   "baseWeeklyHours": 20,
+  // Nobody can carry more than this. Past it the subject needs a second teacher.
+  "maxWeeklyHours": 36,
   "weeksPerMonth": 4,
-  "extraSubjectSurcharge": 0.25,
 }