[Feature request] Remove the white border of image when copy as image a view (Shift + Ctrl + C)

Because there is no way to have a transparent background (#731) , I add a black note behind the diagram to simulate a black background.

When we copy as image, there is always a white border/padding. Is there a way / or an option to remove this border to make copy / paste to content with non-white background ?

Start by tracing the Shift + Ctrl + C copy-as-image action in the Archi desktop application and inspect how the exported image bounds and padding are chosen. Confirm the behavior against a diagram with a black note or non-white destination, then verify that copied images no longer include the unwanted white border or that the requested option works.

Written by the indexing model from the issue text.