Add android ci

.github/workflows/android.yml

@@ -0,0 +1,34 @@
+name: "Android CI: build and test"
+
+on:
+  push:
+    branches: [ "master", "add-ci" ]
+  pull_request:
+    branches: [ "master" ]
+  workflow_dispatch: # Allows you to run the workflow manually from the Actions tab
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          java-version: '21'
+          distribution: 'temurin'
+          cache: gradle
+
+      - name: Grant execute permission for gradlew
+        run: chmod +x gradlew
+      - name: Build with Gradle
+        run: ./gradlew build
+      - name: Build APK
+        run: ./gradlew assembleRelease
+      - name: Upload APK
+        uses: actions/upload-artifact@v4.5.0
+        with:
+          name: app-release
+          path: app/build/outputs/apk/release/app-release-unsigned.apk