ci: Setup GitHub Actions workflow to build and export Android APK

.github/workflows/build-apk.yml

@@ -0,0 +1,38 @@
+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 repository
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+
+      - name: Grant execute permissions to gradlew
+        run: chmod +x gradlew
+
+      - name: Build Debug APK
+        run: ./gradlew assembleDebug --stacktrace
+
+      - name: Upload Debug APK
+        uses: actions/upload-artifact@v4
+        with:
+          name: LibreCast-Receiver-Debug-APK
+          path: app/build/outputs/apk/debug/app-debug.apk