fix: replace removed ShadowNode::Shared with std::shared_ptr<const ShadowNode>

[tomekzaw]

Details

Upstream React Native removed the ShadowNode::Shared type alias, which broke the iOS Fabric build on Expo SDK 56+ / RN nightly with errors like no type named 'Shared' in 'facebook::react::ShadowNode'. This replaces the four usages of ShadowNode::Shared in MarkdownTextInputDecoratorShadowNode (.h and .mm) with std::shared_ptr<const ShadowNode>, matching the current YogaLayoutableShadowNode::appendChild / replaceChild override signatures.

Other ::Shared usages in the project (ShadowNodeFamily::Shared, Props::Shared) are still defined upstream and remain unchanged.

Related Issues

Closes #755

Manual Tests

• Build the example app on iOS with the New Architecture enabled against an RN version that removed ShadowNode::Shared (Expo SDK 56 / RN nightly).
• Build the example app on iOS against the currently-pinned RN 0.83.1 to confirm no regression on the older signature.

Linked PRs

N/A

[os-botify]

🚀 Published to npm in 0.1.326 🎉