Add a build workflow

.github/workflows/build.yml

@@ -0,0 +1,25 @@
+name: Build
+
+on: [ workflow_dispatch, pull_request, push ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: gradle/actions/wrapper-validation@v3
+      - uses: actions/setup-java@v4
+        with:
+          distribution: temurin
+          java-version: 8
+          cache: 'gradle'
+
+      - name: Build with Gradle
+        run: ./gradlew shadowJar --stacktrace --no-daemon
+
+      - name: Upload artifacts
+        uses: actions/upload-artifact@v4
+        with:
+          name: randomcart-artifacts
+          path: build/*.jar
+          compression-level: 0