fix: double-tap like targeting wrong gallery after scrolling
PinchZoomOverlay's updateUIView was empty, so the coordinator kept a
stale onDoubleTap closure when LazyVStack reused cells. Now updateUIView
refreshes the coordinator's parent reference so the gesture always fires
against the correct gallery.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>