[Feature]: Improve event popover for multi-day events

[tobiasge]

Problem / Motivation

When I have multi-day events in my calendar the popover only show the start date.

Proposed Solution

Show the end date of the event when it's different from the start date.

Alternatives Considered

No response

Feature Area

Calendar

Mockups / Examples

No response

Additional Context

No response

[franko-c]

seems like endDate in event-detail-popover.tsx is computed but the date section only renders startDate — multi-day events never show their end date in the popover.