Persistent marker after copying from toolbox

[microbit-robert]

I've discovered a flow that can cause a persistent blue marker to appear at a next/previous connection.

Steps to reproduce:

• Navigate to a next/previous connection
• Hit "T" to open the toolbox
• Navigate to a block and use the keyboard shortcut to copy the block
• The flyout is closed and a blue marker remains at the next/previous position if you do not immediately paste
• It is persistent during further keyboard navigation until some other meaningful block interaction

Video:
https://github.com/user-attachments/assets/a66a7720-1d05-4621-9b80-2b4c2e2020e9