ci: build Android packages in release workflow

Provision Java, Android SDK and NDK, and Rust Android targets in GitHub Actions. Initialize the Tauri Android project, build APK and AAB packages, upload workflow artifacts, and attach them to tagged releases. Document local Android packaging and signing requirements.

.github/workflows/release.yml

@@ -48,4 +48,59 @@ jobs:
           releaseName: 'Cipher Master ${{ github.ref_name }}'
           releaseBody: 'Download the compiled standalone application binaries below.'
           releaseDraft: true
-          prerelease: false
+          prerelease: false
+
+  android:
+    name: Android APK and AAB
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Java
+        uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: '17'
+
+      - name: Setup Android SDK
+        uses: android-actions/setup-android@v3
+
+      - name: Install Android SDK packages
+        run: sdkmanager "platform-tools" "platforms;android-35" "build-tools;35.0.0" "ndk;27.2.12479018"
+
+      - name: Install Rust
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          targets: aarch64-linux-android, armv7-linux-androideabi, i686-linux-android, x86_64-linux-android
+
+      - name: Install Tauri CLI
+        run: cargo install tauri-cli --version '^2.0' --locked
+
+      - name: Initialize Android project
+        working-directory: src-tauri
+        run: cargo tauri android init
+
+      - name: Build Android packages
+        working-directory: src-tauri
+        run: cargo tauri android build --apk --aab
+
+      - name: Upload Android packages
+        uses: actions/upload-artifact@v4
+        with:
+          name: cipher-master-android-${{ github.ref_name }}
+          path: |
+            src-tauri/gen/android/app/build/outputs/apk/**/*.apk
+            src-tauri/gen/android/app/build/outputs/bundle/**/*.aab
+          if-no-files-found: error
+
+      - name: Attach Android packages to GitHub release
+        uses: softprops/action-gh-release@v2
+        if: startsWith(github.ref, 'refs/tags/')
+        with:
+          files: |
+            src-tauri/gen/android/app/build/outputs/apk/**/*.apk
+            src-tauri/gen/android/app/build/outputs/bundle/**/*.aab
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}