feat(admob): demonstrate native ads

[polmiro]

Summary

Expands the Google Mobile Ads Next-Gen example app with native ad workflows:

• add direct native loading for single and batched ads
• add native preloading with configurable poll-and-render counts
• replace previously rendered native ads when loading again

Screenshots

---

Note

Low Risk
Changes are confined to the example app and documentation, with no production SDK or billing/auth impact.

Overview
Replaces the Native placeholder in the AdMob Next-Gen sample with a full NativeScreen that exercises RevenueCat’s native tracking APIs end to end.

Users can switch between standard and native-video test ad units (new ADMOB_NATIVE_VIDEO_AD_UNIT_ID in local.properties / BuildConfig), then try direct loads via loadAndTrackNativeAd or a batch Flow via loadAndTrackNativeAds, or preloaded inventory with start/stop, buffer sizing, and Poll + Show using startAndTrack / pollAndTrackAd. Loaded ads render in NativeAdView cards; non-native result types are tracked and destroyed with explicit status messaging, and in-flight loads clean up SDK-owned ads on cancel or mode changes.

AdScreen gains an optional onModeChange hook so switching Direct/Preloaded clears native UI state; README coverage notes mention standard/video selection.

^{Reviewed by Cursor Bugbot for commit 80f65d6. Bugbot is set up for automated code reviews on this repo. Configure here.}

[RevenueCat-Danger-Bot]

	1 Message
📖	This PR changes 407 lines of production Kotlin/Java (limit 300); skipped via skip-pr-lines-changed-check label.

Generated by 🚫 Danger

[emerge-tools]

📸 Snapshot Test

621 unchanged

Name	Added	Removed	Modified	Renamed	Unchanged	Errored	Approval
TestPurchasesUIAndroidCompatibility com.revenuecat.testpurchasesuiandroidcompatibility	0	0	0	0	339	0	N/A
TestPurchasesUIAndroidCompatibility Paparazzi com.revenuecat.testpurchasesuiandroidcompatibility.paparazzi	0	0	0	0	282	0	N/A

---

🛸 Powered by Emerge Tools

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, have a team admin enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit d3255b1. Configure here.}