Add GitHub workflows

Change-Id: Ic4c802b336a3f7091edbcf86777baa9ea87aeede
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..34d4968
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,27 @@
+name: CI
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up JDK 21
+        uses: actions/setup-java@v4
+        with:
+          distribution: 'temurin'
+          java-version: '21'
+      - name: Build with Gradle
+        run: ./gradlew build --no-daemon
+      - name: Run tests
+        run: ./gradlew test --no-daemon
+      - name: Upload build artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: korapxmltool-jar
+          path: app/build/libs/*.jar