enable CI

.github/workflows/build.yml

@@ -0,0 +1,30 @@
+name: Build Debug APK
+
+on:
+  push:
+    paths-ignore:
+      - '**.md'
+
+jobs:
+  build:
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Set up JDK 17
+        uses: actions/setup-java@v4
+        with:
+          distribution: 'adopt'
+          java-version: '21'
+
+      - name: Build with Gradle
+        run: ./gradlew assembleDebug
+
+      - name: Upload artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: app-debug.apk
+          path: app/build/outputs/apk/debug/app-debug.apk