cropThumbnailImage was filling the target box by aspect-cover — for a
portrait crop served to a landscape device (or vice versa), that meant
slicing a thin band through the photo, which the user correctly called
out as unacceptable on the screen.
Switching to thumbnailImage(... bestfit=true) + composite onto a white
canvas of exact target dims means the photo always shows up upright and
recognizable: matching aspect renders byte-identically to before (no
padding, no zoom change), mismatched aspect shows the photo fit-to-box
with white bars instead of a cropped slice.
Adds an app:rerender-assets console command to reset every Ready asset
to Pending and re-dispatch its render message — needed once after this
deploy so existing bins (rendered with the old cropThumbnail logic) get
regenerated with the letterbox pipeline.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
