What the component handles
- Calendar dropdown with role="dialog" and modal behavior
- Arrow key navigation between dates within the calendar grid
- Month/year navigation buttons are properly labeled
- Date buttons have full date labels (e.g., "28 August 2025, Thursday")
- Selection states are announced clearly ("Selected as start date", "Selected as end date", "Selected")
- aria-pressed state for selected dates and aria-disabled for unavailable dates
Color contrast
All states meet the 4.5:1 text contrast requirement.