Research perfect edge rendering around the output port

[vitvakatu]

We have a few issues with rendering edges coming out of the node.

One is introduced by #11582 for transparent visualizations:

Another one happens when the outcoming edge is dragged horizontally at some specific distance:

Finally, the need to preserve a clear gap between the node and the output port requires as to use SVG masks which causes significant performance drop for nodes with a lot of output connections:

https://github.com/user-attachments/assets/301ea720-c8f0-4df3-b416-9bc26addf871

We investigated an alternative approach – using clipPath instead of masks, but the performance is still insufficient (see internal discussion).

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We should consider either:

1. A design change (e.g. no gap between the output port and the node)
2. Another technical solution for all these issues (should be more straightforward after #11622)