[RN][Refactor]: Rename React Native dismissal callbacks to onDismiss

[kieran-osgood-shopify]

What changes are you making?

Closes https://github.com/shop/issues-checkout-kit/issues/1261

Rename the React Native checkout dismissal callbacks to use one public API name:

• PresentCallbacks.onClose → onDismiss
• AcceleratedCheckoutButtons.onCancel → onDismiss

This is an intentional breaking rename without compatibility aliases. The private native lifecycle event remains close.

Document and test that checkout completion and presentation dismissal are separate events: CheckoutProtocol.complete reports order completion, while onDismiss reports a later buyer dismissal. Programmatic dismiss() invokes neither onDismiss nor onFail.

Register accelerated checkout's onDismiss as a direct native event. React Native already reserves topDismiss as a direct event for modal dismissal; registering it as bubbling caused an event-type collision and an iOS RedBox during app startup.

Update the sample, API report, README, JavaScript tests, and iOS integration coverage.

How to test

GIVEN the React Native sample is configured with a storefront and has an item in the cart

WHEN the reviewer taps Checkout and closes the checkout presentation before completing payment

THEN the sample should log onDismiss once and return to the cart without invoking onFail

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GIVEN the React Native sample is configured with a storefront, has an item in the cart, and can complete a test payment

WHEN the reviewer completes checkout and then dismisses the confirmation presentation

THEN CheckoutProtocol.complete should be logged when the order completes, followed by onDismiss only when the buyer dismisses the presentation

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GIVEN the iOS React Native sample is built with the New Architecture and launched on iOS 16 or newer

WHEN the reviewer opens the catalog and navigates to the cart

THEN the app should render without a RedBox reporting that RCTAcceleratedCheckoutButtons re-registered topDismiss as a bubbling event

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GIVEN the Android React Native sample is built with the New Architecture

WHEN the reviewer launches the app and opens the catalog

THEN the app should render without a LogBox warning about topDismiss being registered as both a direct and bubbling event

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Before you merge

Important

• I've added tests to support my implementation
• I have read and agree with the Contribution Guidelines
• I have read and agree with the Code of Conduct
• I've updated the relevant platform README (platforms/react-native/README.md)

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Releasing a new Swift version?

• I have bumped the version in ShopifyCheckoutKit.podspec
• I have bumped the version in platforms/swift/Sources/ShopifyCheckoutKit/ShopifyCheckoutKit.swift
• I have updated the SwiftPM/CocoaPods version snippets in platforms/swift/README.md (major version only)

Releasing a new Embedded Checkout Protocol version?

• I have bumped embeddedCheckoutProtocolAndroid in platforms/android/gradle/libs.versions.toml
• I have updated protocol/languages/kotlin/embedded-checkout-protocol/api/embedded-checkout-protocol.api if the public API changed

Releasing a new Android version?

• I have bumped checkoutKitAndroid in platforms/android/gradle/libs.versions.toml
• I have updated the Gradle/Maven version snippets in platforms/android/README.md

Tip

See the Contributing documentation for the full release process per platform.

[kieran-osgood-shopify]

🟡 Before this PR is merged, update checkoutKit.nativeSdkVersions.ios and .android in package.json to 4.0.0-alpha.7 after those native artifacts are published. This lifecycle contract depends on the alpha.7 native dismissal behavior.