Adjusted the default value, minValue, and step for the volume knob to improve precision. Removed unused `KnobBackgroundCls` and cleaned up unnecessary whitespace for better readability and maintainability.
Updated the version from 2.0.0-SNAPSHOT to 2.0.0 in `build.gradle.kts` for release readiness. Added a new `test-app` project including Gradle build files, scripts, and configuration for Kotlin multiplatform with JS and JVM targets to enable testing and application runtime.
