The bubble-in-text-input morph ran concurrently with listNode's
scroll-to-item sublayerTransform animation, but its source rect was
computed via CALayer.convert which uses model transforms only and so
missed the pending additive sublayerTransform. The morph's `from`
ended up calibrated to the post-scroll state while playback started
from the pre-scroll state, offsetting the bubble at t=0.
Add convertAnimatingSourceRectFromWindow: walks the layer chain
top-down and at each parent->child step subtracts the parent's pending
additive sublayerTransform translation in the parent's bounds space
before descending, so the result reflects the t=0 presentation state
even through rotations/scales later in the chain. Parent
animatingItemNode under itemNode so listNode is on its ancestor chain
and its pending sublayerTransform is picked up.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
