ci: [SDK-4690] add Android E2E workflow

.github/actions/setup-demo/action.yml

@@ -0,0 +1,50 @@
+name: 'Setup Demo'
+description: 'Installs the JDK and Android toolchains, caches Gradle, and writes the demo local.properties file'
+inputs:
+  onesignal-app-id:
+    description: 'OneSignal App ID written into examples/demo/local.properties'
+    required: true
+runs:
+  using: 'composite'
+  steps:
+    - name: Set up Java
+      uses: actions/setup-java@v4
+      with:
+        distribution: temurin
+        java-version: '17'
+
+    - name: Set up Android SDK
+      uses: android-actions/setup-android@v3
+      with:
+        cmdline-tools-version: '10406996'
+        log-accepted-android-sdk-licenses: false
+
+    - name: Cache Gradle
+      uses: actions/cache@v4
+      with:
+        path: |
+          ~/.gradle/caches
+          ~/.gradle/wrapper
+        # `*.gradle*` matches `build.gradle{,.kts}` etc. but NOT `gradle.properties`
+        # (no literal `.gradle` substring), so list `gradle.properties` explicitly.
+        key: ${{ runner.os }}-gradle-demo-${{ hashFiles('examples/demo/**/*.gradle*', 'examples/demo/**/gradle.properties', 'examples/demo/**/gradle-wrapper.properties') }}
+        restore-keys: |
+          ${{ runner.os }}-gradle-demo-
+          ${{ runner.os }}-gradle-
+
+    # Mirrors the Capacitor demo's `.env`: writes the override file before any
+    # build runs so the OneSignal App ID + channel id end up baked into
+    # BuildConfig. `examples/demo/app/build.gradle.kts` resolves each key in
+    # this order: `-PKEY=value` from the CLI > local.properties > built-in
+    # default, so writing to local.properties is the closest equivalent to
+    # the Capacitor `.env` flow.
+    - name: Write demo local.properties
+      shell: bash
+      working-directory: examples/demo
+      env:
+        ONESIGNAL_APP_ID: ${{ inputs.onesignal-app-id }}
+      run: |
+        {
+          echo "ONESIGNAL_APP_ID=${ONESIGNAL_APP_ID}"
+          echo "ONESIGNAL_ANDROID_CHANNEL_ID=7ec2ece9-c538-4656-9516-1316f48a005c"
+        } > local.properties

.github/workflows/e2e.yml

@@ -0,0 +1,93 @@
+name: E2E Tests
+
+on:
+  push:
+    branches:
+      - rel/**
+  workflow_dispatch:
+    inputs:
+      sdk-version:
+        description: 'OneSignal Android SDK version to wait for and build against (defaults to OneSignalSDK/gradle.properties).'
+        required: false
+        type: string
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build-android:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      # Fail fast on unset var. Otherwise `demoOverride()` collapses "" to
+      # null and the build silently uses the hardcoded default app ID.
+      - name: Validate APPIUM_ONESIGNAL_APP_ID
+        env:
+          ONESIGNAL_APP_ID: ${{ vars.APPIUM_ONESIGNAL_APP_ID }}
+        run: |
+          if [ -z "$ONESIGNAL_APP_ID" ]; then
+            echo "::error::APPIUM_ONESIGNAL_APP_ID is not set"
+            exit 1
+          fi
+
+      - name: Set up demo
+        uses: ./.github/actions/setup-demo
+        with:
+          onesignal-app-id: ${{ vars.APPIUM_ONESIGNAL_APP_ID }}
+
+      - name: Resolve OneSignal Android SDK version
+        id: android-sdk-version
+        env:
+          INPUT_VERSION: ${{ github.event.inputs.sdk-version }}
+        run: |
+          if [ -n "$INPUT_VERSION" ]; then
+            VERSION="$INPUT_VERSION"
+          else
+            VERSION=$(grep -E '^SDK_VERSION=' OneSignalSDK/gradle.properties | cut -d '=' -f2)
+          fi
+          if [ -z "$VERSION" ]; then
+            echo "::error::Could not resolve OneSignal Android SDK version"
+            exit 1
+          fi
+          echo "Resolved OneSignal Android SDK version: $VERSION"
+          echo "version=${VERSION}" >> "$GITHUB_OUTPUT"
+
+      - name: Wait for OneSignal Android SDK on Maven Central
+        uses: OneSignal/sdk-shared/.github/actions/wait-for-maven-artifact@main
+        with:
+          version: ${{ steps.android-sdk-version.outputs.version }}
+
+      # gms+debug: BrowserStack devices have GMS, debug enables UiAutomator2
+      # attach. -PSDK_VERSION pins the Maven dep to the version we waited
+      # for. SDK_VERSION flows through env: to avoid script injection
+      # (workflow_dispatch input is user-controlled).
+      - name: Build debug APK
+        working-directory: examples/demo
+        env:
+          SDK_VERSION: ${{ steps.android-sdk-version.outputs.version }}
+        run: ./gradlew :app:assembleGmsDebug "-PSDK_VERSION=$SDK_VERSION" --console=plain --warning-mode=summary
+
+      - name: Upload APK
+        uses: actions/upload-artifact@v4
+        with:
+          name: demo-apk
+          path: examples/demo/app/build/outputs/apk/gms/debug/app-gms-debug.apk
+          retention-days: 1
+          compression-level: 0
+
+  e2e-android:
+    needs: build-android
+    uses: OneSignal/sdk-shared/.github/workflows/appium-e2e.yml@main
+    secrets: inherit
+    with:
+      platform: android
+      app-artifact: demo-apk
+      app-filename: app-gms-debug.apk
+      sdk-type: android
+      build-name: android-${{ github.ref_name }}-${{ github.run_number }}