feat: support Android Native UI extensions with Kotlin and Compose

[rdlabo]

Android apps can now render app-local Native UI extensions with Kotlin and Jetpack Compose, using the same DOM readers, props and action targets as iOS. Standard Ionic and HTML controls remain on the Web; Android supports element placement only, without Vertical Bars or tab accessories.

• Replace the Android stub with a Kotlin plugin and public Compose registration API.
• Share DOM discovery, geometry tracking, state updates and markForCheck(); convert source frames to dp and forward native actions to their original DOM targets with acknowledgement.
• Handle suspension, Activity pause/resume, source removal and teardown, while keeping unsupported or rejected extensions on the Web.
• Document Kotlin/Compose setup and platform support in the existing user guides. Exclude Android build output from Git and formatting checks.

Validation:

• Package build, lint and package archive/consumer verification passed.
• Web unit tests: 79 passed across 15 files.
• Android debug library and sample APK builds passed; 3 Kotlin snapshot validation tests passed.
• Local Android emulator: Compose rendering, DOM click acknowledgement and state updates, Activity background/foreground, shell suspend/resume, and source position/size changes verified. Standard HTML buttons retained Web presentation.

Android smoke testing used a temporary Capacitor app; no additional demo Android project is included.

[github-actions]

Playwright test results

 456 passed

Details

 456 tests across 24 suites
 5 minutes, 7 seconds
 2ec6b32
 This detailed result covers Ionic 9 only. Ionic 8 runs against the same screenshots in a separate matrix job; check the workflow run for both results. To update the screenshots, comment with /update-screenshots.

[github-actions]

📊 Ionic 9 Playwright Test Report

View the detailed Ionic 9 report: https://rdlabo-dev.github.io/ionic-theme-ios27/pr-290/

Ionic 8 runs against the same screenshots in a separate matrix job. View both results in the workflow run.