- the time zone is used to calculate the date
- use the offset to know if beginsOn and endsOn are the same day
- refactor the <o-switch>
Solves, for example, this display problem :
The date range "2024-12-31 17:45 to 2025-01-01 01:00" in the Asia/Shanghai time zone (spanning different years and days) is equivalent to "2024-12-31 at 10:45 to 2024-12-31 at 18:00" in the Europe/Paris time zone (same year and same day).