feat: add Expo scene deep-link readiness (MBL-2304)

[Shahroz16]

Summary

• buffer SDK-originated scene deep links until the JavaScript Linking listener is ready
• expose CustomerIO.setDeepLinkRoutingReady() for Expo native auto-initialization
• log when a URL is actually buffered so a missing readiness call is diagnosable without warning on healthy launches
• install Expo scene routing without changing AppDelegate-only or Android behavior

Packaging note

• set the CocoaPods header_dir so static-framework Expo builds resolve the React Native wrapper module consistently; this changes the installed public-header directory but not the supported JavaScript API

Validation

• TypeScript, lint, and Jest tests pass
• Android compileDebugKotlin passes
• generated Expo SDK 58 projects build with static and dynamic CocoaPods linkage
• warm and cold scene URL routing was exercised in the iOS simulator
• simulator notification delivery and tap reached React Native Linking after native auto-init readiness

Part of MBL-2304.

[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.

---

• iOS FCM: 646.7.0 (29796720)
• iOS APN: 646.7.0 (29796720)

[mrehan27]

Approving. The buffering design holds up — I traced readiness end to end and the split is right: JS-init hosts are covered automatically by markReactNativeReady() in initialize, and the new API exists only for natively-initialized hosts that never call it. README is thorough and accurate.

Comments are hardening, not blockers. The test-coverage one is worth doing before merge, since customerio/customerio-expo-plugin#398 will bind to this behavior once released.