Add GitHub Actions workflow for automated APK builds

.github/workflows/build.yml

@@ -0,0 +1,34 @@
+name: Build Android APK
+
+on:
+  push:
+    branches: [ main, master ]
+  pull_request:
+    branches: [ main, master ]
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v3
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v3
+        with:
+          distribution: 'temurin'
+          java-version: '17'
+          cache: gradle
+
+      - name: Grant execute permission for gradlew
+        run: chmod +x gradlew
+
+      - name: Build with Gradle
+        run: ./gradlew assembleDebug
+
+      - name: Upload APK
+        uses: actions/upload-artifact@v3
+        with:
+          name: app-debug
+          path: app/build/outputs/apk/debug/app-debug.apk