fix: [SDK-4841] prewarm dispatchers at process start via ActivityLifecycleInitializer

[abdulraqeeb33]

Prewarms OneSignalDispatchers as the first step of ActivityLifecycleInitializer.create(), before activity lifecycle callbacks are registered, so the process-start lifecycle path gets the same dispatcher warmup head start as the other cold-start entry points.

Also updates the prewarm() KDoc entry-point table and adds focused unit coverage verifying the initializer calls prewarm() before lifecycle callback registration while stubbing the real warmup via IOMockHelper.

Verification note: attempted :OneSignal:core:testOriginalDebugUnitTest --tests 'com.onesignal.core.internal.application.impl.ActivityLifecycleInitializerTests' and :OneSignal:core:detekt, but this sandbox has no java on PATH and JAVA_HOME is unset.

[github-actions]

📊 Diff Coverage Report

Diff Coverage Report (Changed Lines Only)

Gate: aggregate coverage on changed executable lines must be ≥ 80% (JaCoCo line data for lines touched in the diff).

Changed Files Coverage

• ActivityLifecycleInitializer.kt: 1/1 touched executable lines (100.0%) (4 touched lines in diff)

Overall (aggregate gate)

1/1 touched executable lines covered (100.0% — requires ≥ 80%)

📥 View workflow run

[fadi-george]

Seems good.

[nan-li]

Verification note: attempted :OneSignal:core:testOriginalDebugUnitTest --tests 'com.onesignal.core.internal.application.impl.ActivityLifecycleInitializerTests' and :OneSignal:core:detekt, but this sandbox has no java on PATH and JAVA_HOME is unset.

?

[abdulraqeeb33]

Verification note: attempted :OneSignal:core:testOriginalDebugUnitTest --tests 'com.onesignal.core.internal.application.impl.ActivityLifecycleInitializerTests' and :OneSignal:core:detekt, but this sandbox has no java on PATH and JAVA_HOME is unset.

?

Tests seem to run fine on CI. I created this PR on the cloud and it doesn't have JAVA in there.