test: validate React Native scene host on Xcode 27 (MBL-2234)

[Shahroz16]

Test only, do not merge

Validates production #641 against an exact React Native 0.88 nightly scene host on the Xcode 27 runner.

The workflow pins the CLI, compatible stable template, React Native package, and companion @react-native/* packages. It installs the autolinked wrapper plus APN and Live Activities subspecs, keeps the real CioAppDelegateWrapper, uploads both lockfiles, and validates the built scene manifest.

The behavioral check requires an SDK-triggered warm URL to reach React Native Linking exactly once. The scene host also compiles and calls the production cold connection-options helper, but the simulator does not provide a terminated simctl openurl through connectionOptions.urlContexts. A real cold Live Activity tap therefore remains in the physical-device matrix rather than being claimed here.

This is simulator evidence only. After the hosted evidence and independent review are recorded, close this PR without merging.

[github-actions]

Sample app builds 📱

Below you will find the list of the latest versions of the sample apps. It's recommended to always download the latest builds of the sample apps to accurately test the pull request.

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• Android APN: 640.17.0 (29791759)
• iOS APN: 640.17.0 (29791759)

[Shahroz16]

Final evidence for 044b82be013617a93cfbecfee6751d6f863f2829:

• Xcode 27 run 32653626934 passed.
• The fixture pinned React Native 0.88.0-nightly-20260823-0c7f63a4e, generated the upstream scene host, installed the APN and Live Activities subspecs, built with the iOS 27 SDK, and validated the built scene manifest.
• The app launched on the iOS 27 simulator and remained alive for 30 seconds. Its in-app guard would terminate the process unless scene(_:willConnectTo:options:) ran and the SDK-triggered warm URL completed the React Native Linking round trip exactly once.
• This does not claim terminated Live Activity delivery. simctl openurl does not populate cold connectionOptions.urlContexts; that remains physical-device evidence in MBL-2233.

This PR is test-only and is being closed without merge.