fix(android): tie observer cleanup to the React module lifetime

[OskarEichler]

Description

One Line Summary

Remove the activity lifecycle listener, whose destroy callback removed observers even while the React instance remained usable. Keep cleanup in invalidate and release retained notification events and the current static instance there.

Compatibility and observable changes

Observers remain available across host activity recreation until module invalidation. Invalidating an old module does not clear a newer current instance. No JS API changes.

Details

Motivation

The source audit reproduced the failure paths described below. This PR contains only the associated fix; unrelated audit changes are in separate PRs.

Scope

• android/src/main/java/com/onesignal/rnonesignalandroid/RNOneSignal.java

Testing

Compiled actual constructor/invalidate methods and activity lifecycle reproduction; checked ReactContext and LifecycleEventListener source to distinguish activity destruction from React instance invalidation.

Each code/tooling fix was also applied independently to upstream commit a70312207cf094ac361eaa9196c317acb175c2cd and passed its targeted external actual-source diagnostics. Documentation snippets were checked separately. Native diagnostic harnesses use bridge/SDK doubles and are not an end-to-end push test.

On the combined audit branch:

• Existing SDK suite: 5 files, 262 tests pass; unchanged 95% coverage thresholds pass.
• vp check: formatting, lint and type checks pass; native Spotless check passes.
• Both example apps: Android Debug and unsigned iOS Simulator builds pass.
• Both example apps: iOS and Android production Metro bundles pass.

No checked-in test files were added or modified; regression evidence comes from external diagnostic harnesses and the existing suite. No physical-device, live notification delivery, Appium/BrowserStack, or release-workflow execution is claimed. The no-location example's stale native lock was updated locally to resolve the current SDK for verification; generated locks are not part of this PR.

Checklist

• Required description sections completed.
• Scope and observable/API behavior explained.
• Diff reviewed and targeted regression checks run.
• Automated checks and device-testing limitations documented.