chore: Release 5.5.2

[onesignal-deploy]

Channels: Current

🛠️ Native Dependency Updates

• Update Android SDK from 5.7.7 to 5.8.0
  • feat: hash PII (email/SMS) in SharedPreferences at rest (#2620)
  • feat: SDK-4176: gate background threading behind remote feature flag (#2595)
  • feat: SDK-4210: Standardize BACKGROUND_THREADING feature flag key naming (#2598)
  • feat: SDK-4363: Turbine remote SDK feature flags and foreground refresh (#2612)
  • bug: catch exception if opening a notification fails (#2508)
  • Fix: a rare NPE from PermissionViewModel (#2504)
  • fix: add retry for notification opened confirmation (#2606)
  • fix: end initialization early if device storage is locked (#2520)
• Update iOS SDK from 5.5.0 to 5.5.1
  • fix: update unattributed outcomes to match attributed outcomes and Android SDK (OneSignal-iOS-SDK#1655)

[claude]

LGTM, mechanical release PR — version bumps and Android SDK 5.7.7 → 5.8.0.

Extended reasoning...

Overview

This PR releases version 5.5.2 of the OneSignal Flutter SDK. Changes are limited to: version bumps in pubspec.yaml, android/build.gradle, and ios/onesignal_flutter.podspec (5.5.1 → 5.5.2); the SDK version constant strings in OneSignalPlugin.java and OneSignalPlugin.m ("050501" → "050502"); and the Android native dependency bump from com.onesignal:OneSignal:5.7.7 to 5.8.0. iOS OneSignalXCFramework is unchanged at 5.5.0.

Security risks

None introduced by this PR itself. The Android SDK update at 5.8.0 actually includes a security-positive change (hashing PII in SharedPreferences at rest), along with several stability fixes. Risks here are inherited from the upstream native SDK release rather than from any logic in the Flutter wrapper.

Level of scrutiny

Low. This is a release/version-bump PR following the established pattern for this repo. There are no logic changes in the Flutter wrapper code — just synchronized version constants and a Gradle dependency line. The wrapper continues to call the same OneSignal SDK APIs unchanged.

Other factors

The version string is consistently updated everywhere it needs to be (pubspec, podspec, build.gradle, and both native SDK version constants). The comment 'Keep in sync with pubspec.yaml version' is respected. No outstanding reviewer comments on the timeline.