Event sidebar does not update correctly when dragging an event between days

### What Happened?

An event was dragged to the following day and then dragged back. The sidebar ended up with multiple copies of the event.

### Steps to Reproduce

1. Drag an event to the following day
2. Drag it back

### Expected Behavior

The sidebar should remove references to an event when it is being dragged and add them back only as appropriate when it is dropped, or otherwise ensure the sidebar reflects the true list of events.

### OS Version

8.x (Circe)

### OS Architecture

amd64 (on most hardwares)

### Session Type

Secure Session (Wayland, This is the default)

### Software Version

Latest release (I have run all updates)

### Log Output

```shell

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### Hardware Info

_No response_