[Task]: Kotlin embedder: Spec 139 app_command parity and adapter registration

[enricopiovesan]

Summary

Bring packages/kotlin/TraverseEmbedder to embedder-api 1.1.0 parity: app_command submit, timer port, host-connector waits and adapter registration.

Governing spec

specs/139-embedder-app-state-machine-execution/spec.md; Spec 140

Why

Cross-platform conformance (Spec 057/529) requires every published embedder to pass the same suite.

Depends on

#1468

Blocked by

Adapter registration waits on the Spec 140 governance PR; the rest is not blocked. Maven publication is #1371.

Definition of done

• app_command, timer port, host-connector wait, adapter registration
• Passes the shared conformance suite

Validation

• Gradle tests in packages/kotlin/TraverseEmbedder

[enricopiovesan]

Blocked in validation setup: Gradle requires Android API 35, but this host has no Java runtime. Installing the documented Temurin JDK requires an interactive administrator password, which the automation session cannot provide. After a JDK is installed, run sdkmanager --sdk_root=/opt/homebrew/share/android-commandlinetools "platforms;android-35" "build-tools;35.0.0", configure sdk.dir=/opt/homebrew/share/android-commandlinetools (or ANDROID_HOME), then resume the Kotlin embedder tests.