Add GitHub workflow action for Android build (#124)

Author: Copilot

.github/workflows/android-build.yml

@@ -0,0 +1,54 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+name: Android Build
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: LlamaDemo
+            path: llm/android/LlamaDemo
+          - name: DeepLabV3Demo
+            path: dl3/android/DeepLabV3Demo
+
+    name: Build ${{ matrix.name }}
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v4
+
+      - name: Build with Gradle
+        working-directory: ${{ matrix.path }}
+        run: ./gradlew build --no-daemon
+
+      - name: Upload build artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: ${{ matrix.name }}-apk
+          path: ${{ matrix.path }}/app/build/outputs/apk/
+          if-no-files-found: warn