Bugfix: Jump to a scroll target unless that call is inside an animated transaction

[shiaho777]

ScrollViewProxy.scrollTo decided whether to animate by reading Animation.isInWithAnimation inside a coroutine. That flag is the marker left for one frame after some other withAnimation, so a later scrollTo from onChange or a task used animateScrollToItem and traveled the whole list.

The decision is now taken on the calling thread, before the coroutine starts. A scroll animates only when the transaction active for that call has an animation. The post-exit marker does not count. TabView still uses the marker for its own page sync.

This addresses Issue #469.

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• AI was used to generate or assist with generating this PR. Please specify below how you used AI to help you, and what steps you have taken to manually verify the changes.

An AI assistant drafted the scroll decision and the Swift tests. swift test passed, including the transpiled Android unit tests that command runs locally. ScrollToMotionTests passed. No Android emulator or device was used, so the Compose scroll itself was not checked on a device. Skip Fuse UI depends on SkipUI and does not duplicate these scroll containers, so it does not need a separate change.

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