Add nightly CI

.github/workflows/gradle.yml

@@ -0,0 +1,33 @@
+name: Nebula Nightly
+
+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:
+        java-version: '21'
+        distribution: 'temurin'
+
+    - name: Setup Gradle
+      uses: gradle/actions/setup-gradle@af1da67850ed9a4cedd57bfd976089dd991e2582
+
+    - name: Build
+      run: |
+            chmod +x gradlew
+            ./gradlew jar
+
+    - name: Upload artifact
+      uses: actions/upload-artifact@v4
+      with:
+        name: Nebula-Nightly
+        path: Nebula.jar