Instrument Swift checkout failures

[tiagocandido]

Summary

• Record Swift checkout errors, protocol decoding failures, navigation retry outcomes, and monotonic navigation duration
• Add a default-on telemetry setting with an explicit runtime opt-out that discards buffered measurements
• Prevent duplicate HTTP/navigation error metrics and align retry funnel semantics (started, failed, not_attempted)
• Route the product attribute per entry point (accelerated_checkouts vs checkout_kit) and report react-native-swift as the platform when embedded in React Native
• Lazily initialize the recorder and keep production transport out of unit tests
• Guard recorder creation against a concurrent runtime opt-out
• Document the bounded diagnostic data and explicit opt-out

Validation

• Swift formatting
• Full Swift unit test suite
• Swift API compatibility checks

[tiagocandido]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• Instrument web checkout failures #678
• Complete React Native telemetry opt-out #677
• Instrument Android checkout failures #676
• Instrument Swift checkout failures #675 👈 (View in Graphite)
• Add internal Checkout Kit telemetry foundations #674
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[bitrise]

Install this build

Open Tophat, select your target device, then click Install. Links open on the Mac running Tophat.

SDK	Install
Swift	Install with Tophat

Checkout Kit E2E results

Status	Suite	Target	Platform	OS version tag	Device
✅	swift-ios	swift	ios	latest	iPhone 15 iOS 27 Beta