Fix coroutine activity check in DefaultCoreTimer

[rezapour]

Motivation

• Ensure the timer loop respects coroutine cancellation by checking the actual coroutine context isActive instead of the previously imported NonCancellable.isActive.

Description

• In core/timer-core/src/main/java/me/rezapour/timer_core/impl/DefaultTimerEngine.kt replaced import kotlinx.coroutines.NonCancellable.isActive with import kotlinx.coroutines.currentCoroutineContext and import kotlinx.coroutines.isActive, and updated the loop to while (currentCoroutineContext().isActive && _status.value == CoreTimerStatus.Running) so cancellation is evaluated against the running job.

Testing

• Ran ./gradlew test and ./gradlew :core:timer-core:test --stacktrace, both could not complete in this environment due to a Gradle/Kotlin JVM version parse error (IllegalArgumentException: 25.0.1).

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Codex Task