Regenerate multi-panel visual baselines after compare() fix

These baselines now reflect the figures' natural per-panel layout (colorbars and
legends within each panel's column instead of overlapping neighbours). Includes
the new multi-panel color baselines and existing multi-panel tests (group
filtering, datashader reduction grid, multichannel normalization, frameon
multi-panel, raccoon split, visium hex grid, transparent-cmap comparisons).
Generated from the py3.11-stable CI artifact.

Author: timtreis