Translate the shared animated image rectangle into the Before pane for
whole-frame drawing, cached window tiles and input mapping. Translate the
final target separately so render requests stay stable during the motion.
Cover intermediate mesh bounds and final geometry in both layouts,
including clicks in either pane, return to Fit and cached region tiles.
Fixes#1821
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>