Added FOCUS-58998 - System Preferences: Hide Lunch from Schedules Changed to a DateTime Preference

Enhances the Hide Lunch from Schedules system preference by replacing the previous on/off setting with a date and time option.

Administrators can now specify the exact date and time until which lunch periods should be hidden from student schedules. Once the configured date and time has passed, lunch periods automatically become visible again without requiring additional configuration. Existing settings are automatically converted during upgrade, preserving previous behavior.