feat: Add GitHub Actions workflow for Android CI build

This workflow builds the Android APK on every push and pull request to the main branch.

Author: google-labs-jules[bot]

.github/workflows/android_ci_build.yml

@@ -0,0 +1,33 @@
+name: Android CI Build
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+
+    - name: Set up JDK 17
+      uses: actions/setup-java@v4
+      with:
+        java-version: '17'
+        distribution: 'temurin'
+
+    - name: Make gradlew executable
+      run: chmod +x gradlew
+
+    - name: Build with Gradle
+      run: ./gradlew assembleRelease
+
+    - name: Upload APK
+      uses: actions/upload-artifact@v4
+      with:
+        name: release-apk
+        path: app/build/outputs/apk/release/app-release.apk