Consolidate shared element transition state and hidden view tracking

Summary

Consolidate the shared-element-transition state model.

The current implementation stores hidden view tags in a global hiddenViewTags_ set. This state is not tied to transition state in sharedContainers_. The current sharedContainers_ model stores only before and after nodes. It may not correctly represent sequential shared-element transitions such as A→B→C.

Required changes

• Define shared-transition state that associates hidden views with the relevant shared container or transition lifecycle.
• Update the state model so that sequential transitions, including A→B→C, preserve the required view state and restore each view at the correct time.
• Consolidate ownership, cleanup, and restoration of hidden-view state with shared-transition state.
• Resolve the TODO in packages/react-native-reanimated/Common/cpp/reanimated/LayoutAnimations/LayoutAnimationsManager.cpp at Line 42.

Rationale

A global hidden-view set can become detached from the transition that hides or restores a view. A transition-scoped state model should make cleanup and restoration explicit and support chained transitions.

Affected areas

• packages/react-native-reanimated/Common/cpp/reanimated/LayoutAnimations/LayoutAnimationsProxy.*
• packages/react-native-reanimated/Common/cpp/reanimated/LayoutAnimations/SharedTransitions.cpp
• packages/react-native-reanimated/Common/cpp/reanimated/LayoutAnimations/LayoutAnimationsManager.cpp

Acceptance criteria

• Hidden-view state has an explicit association with its shared transition or shared container.
• A sequential A→B→C shared-element transition does not leave an incorrect source copy visible.
• Views restore only when their associated transition completes or is cleaned up.
• The TODO at Line 42 in LayoutAnimationsManager.cpp is resolved.
• The shared-transition example is verified on iOS and Android.

Backlinks

• Pull request: https://github.com/software-mansion/react-native-reanimated/pull/10425
• Review comment: https://github.com/software-mansion/react-native-reanimated/pull/10425#pullrequestreview-5223227601
• Requested by: @pawicao