Dual VoT 8.5.4 — fix YouTube playback crash
Fixes the crash introduced in 1.49.0-dev.7-dualvot.8.5.3: changing player state could terminate YouTube with NoClassDefFoundError: kotlin.Unit.
- Playback callbacks and the PiP observer no longer link to Kotlin Unit or Function1.
- Java-only Morphe extensions keep Kotlin disabled; the legacy compatibility fixture dependency is test-only.
- Tests include a class loader that cannot load any Kotlin class, legacy event dispatch, and listener removal.
- The compiled MPP is inspected for hard Kotlin Unit/Function1 type references before publication.
Based on Morphe 1.49.0-dev.7. Full Android build, focused runtime regression tests and automation tests passed. Archive integrity, manifest version and license notices were checked. Android device confirmation is pending.