test: add native functional coverage

[JimmyDaddy]

Summary

• add JS wrapper tests for option normalization and image source validation
• move Android and iOS image-watermark rendering into testable native helpers
• add Android instrumentation and iOS XCTest coverage for anchored image watermarks and background rotation
• stabilize iOS CI by selecting an available simulator UDID and forcing JS bundling for Debug simulator tests

Notes

Debug iOS simulator tests need FORCE_BUNDLING=1; without it the app starts with No bundle URL present. The CI test step now sets that explicitly.

Validation

• yarn test --runInBand
• yarn typecheck --pretty false
• npm run prepack
• yarn prettier --check --ignore-unknown .github/workflows/ci.yml src/__tests__/index.test.ts android/src/main/java/com/jimmydaddy/imagemarker/ImageMarkerManager.kt android/src/main/java/com/jimmydaddy/imagemarker/ImageMarkerRenderer.kt example/android/app/build.gradle example/android/app/src/androidTest/java/com/imagemarkerexample/ImageMarkerRendererTest.kt && git diff --check
• cd example/android && ./gradlew :react-native-image-marker:compileDebugKotlin :app:compileDebugAndroidTestKotlin --stacktrace
• cd example/android && ./gradlew test --stacktrace
• cd example/android && ./gradlew connectedCheck --stacktrace
• cd example/android && ./gradlew assembleRelease --stacktrace
• cd example/ios && FORCE_BUNDLING=1 xcodebuild -workspace ImageMarkerExample.xcworkspace -scheme ImageMarkerExample -sdk iphonesimulator -destination id=1E771580-D017-4A27-9999-59F6C2563A4C test | xcpretty
• cd example/ios && xcodebuild -workspace ImageMarkerExample.xcworkspace -scheme ImageMarkerExample -configuration Release -sdk iphonesimulator -destination id=1E771580-D017-4A27-9999-59F6C2563A4C | xcpretty