Platform abstraction decision-making for Amethyst KMP project. Guides when to abstract vs keep platform-specific,
source set placement (commonMain, jvmAndroid, platform-specific), expect/actual patterns. Covers primary targets
(Android, JVM/Desktop, iOS) with web/wasm future considerations. Integrates with gradle-expert for dependency issues.
Triggers on: abstraction decisions ("should I share this?"), source set placement questions, expect/actual creation,
build.gradle.kts work, incorrect placement detection, KMP dependency suggestions.