- Added UpcomingUIModel for managing upcoming manga list items with headers and items.
- Introduced CalendarDay widget to display individual days with event indicators.
- Created CalendarHeader widget for navigating between months.
- Developed CalendarIndicator for visualizing events on specific days.
- Implemented UpcomingCalendar to manage the calendar view and event loading.
- Added UpcomingItem widget for displaying individual upcoming manga with cover images.
- Introduced FetchInterval utility to calculate fetch intervals based on chapter upload dates.
- Refactored updateMangaDetail to utilize FetchInterval for smart update days.
- Enhanced MedianExtension to ensure correct median calculation.
- Removed unused imports and commented-out code for cleaner implementation.
