[Bug] Layout breaks when scrolling room view up then dragging space item down

### Steps to reproduce

1. Open a room with many messages and scroll up a few pages
2. Drag and drop a space item to the bottom
3. The layout breaks — the app is only usable again after refreshing (F5)

https://github.com/user-attachments/assets/c286978a-6e47-48d9-849a-478adb671d8f

### Outcome

#### What did you expect?
Layout should remain intact.
#### What happened instead?

### Operating system

Windows and MacOS

### Browser information

chorme

### URL for webapp

_No response_

### Application version

_No response_

### Homeserver

_No response_

### Will you send logs?

Yes

Reproduce the issue in a room with many messages: scroll up several pages, drag a space item to the bottom, and observe the layout. Start by tracing the room view's scrolling and drag-and-drop handling. Done means the layout remains usable after the drop without requiring a refresh.

Written by the indexing model from the issue text.