Occasional hidden overflow on left edge of proof visualization

There seems to be a discrepancy between the positioning of nodes in the proof visualization and the boundaries of the overall SVG, which sometimes leads to truncation on the left edge. This is a relatively mild example, but I have seen worse:

I cannot currently rule out that it might also happen at the right edge, but I have not observed this yet.

If we end up implementing both this issue and #83, #83 should probably be done first, because this has far-reaching consequences for the positioning of nodes.

Start by reproducing the proof visualization shown in the issue and tracing how node positions and the overall SVG boundaries are calculated. Check the related work in #83 first, then verify that representative visualizations no longer truncate nodes at the left edge and, if applicable, the right edge.

Written by the indexing model from the issue text.