feat: Migrate samples to Kadre and validate kextract-based wgpu4k-native rendering in CI

[ygdrasil-io]

Summary

• Migrated the binding pipeline away from the legacy YAML-generated declarations toward kextract-generated Kotlin bindings.

• Restored missing generated API coverage exposed by the C headers, including function declarations, handle/value-class mappings, texture usage constants, native display handle support, and callback plumbing.

• Adjusted common/JVM/native call sites to match the kextract output more closely, including nullable handles, descriptor types, callback info structs, and generated WebGPU type aliases.

• Kept legacy YAML-era assumptions out of the samples where possible so the demos exercise the generated kextract bindings directly.

• Migrated the JVM desktop sample to use Kadre windowing across supported desktop backends.

• Migrated the Android sample from the custom WGPUSurfaceView flow to Kadre’s KadreActivity / ApplicationHandler model.

• Added an offscreen JVM capture path that renders the wgpu4k-native triangle into a texture, reads it back, writes a PNG, and validates representative pixels.

• Added CI coverage for the visual capture check on macOS, with the generated PNG uploaded as an artifact.

• Aligned the parent build with Kadre’s Android Gradle Plugin version so the composite build can resolve Android Kadre modules.

Validation

./gradlew :demo:desktop-and-ios:verifyJvmCapture
./gradlew :demo:android:assembleDebug
./gradlew :demo:android-native:assembleDebug
./gradlew :demo:android:compileDebugKotlinAndroid :demo:desktop-and-ios:compileKotlinMacosArm64

Notes

• The visual comparison runs on macOS CI for now because the Metal path is the most deterministic available backend in GitHub Actions.
• Desktop native and Android native samples remain on their existing platform-specific paths because Kadre does not currently provide equivalent Kotlin/Native desktop or ANativeActivity backends.