Products with no featured image return featured_image: [] (empty array) rather
than an object or null, which failed to bind to a single ColumbiaImage and
aborted the whole sync. Adds ColumbiaImageJsonConverter that reads the object
when present and yields null for any non-object form ([], false, ""), and drops
the unused GalleryImages property (we only use featured_image) to remove the
same risk. Regression tests cover both the empty-array and object cases.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
spouliot
eed61a298b