TODO comment for marker consideration in auto-positioning

[gb119]

Description:

In src/stonerplots/util.py:410, there's a TODO comment:

# XXX TODO: If markers are present, it would be good to take them
# into account when checking vertex overlaps in the next line.

This indicates that marker bounding boxes may not be considered when automatically positioning inset plots, which could lead to suboptimal placement when plots contain markers.

Recommended Action:

1. Investigate if this is still relevant
2. If relevant, implement marker consideration in auto-positioning logic
3. If not feasible, document as a known limitation
4. If already handled elsewhere, remove the comment