v2.3.0: Update changelog, demo, and core for Version 2.3.0

- Added `Version 2.3.0` section to `changelog.md` with feature, improvement, and bugfix notes.
- Introduced native **Tasks** support with enhanced UI elements and interactions, including status toggling, priorities, due dates, and overdue detection.
- Added demo enhancements showcasing task functionality and interaction with the calendar.
- Fixed issues related to task formatting, styling, and rendering consistency across views.
- Added `onTaskStatusChanged` and `onDuplicate` callbacks with corresponding events.