normalizeGeometry is for geometry that is already spatially
meaningful, with its own coordinates genuinely correspond to the nodes
(e.g. real cell-segmentation boundaries) and only needs realigning
to the current, normalized node frame. It fits a linear regression
between the geometry's centroids and the node coordinates and rescales
the geometry accordingly, warning if the fit is poor (the geometry did
not, in fact, scale linearly with the nodes).
fitGeometry is for geometry that is not yet spatially
related to the nodes, as arbitrary shapes used for node markers. It
repositions every shape so its centroid sits exactly at its node's
coordinates and, when use_node_size = TRUE, also rescales
each shape so its diameter matches nodeSize.
Both require gs to already be normalized (see
normalizeGraphSpace), and both operate on a single named
geometry column, leaving any other geometry columns untouched.