Enhance CI workflow: add concurrency control, test result publishing, and Javadoc generation

.github/workflows/ci.yml

@@ -6,6 +6,11 @@ on:
   pull_request:
     branches: [ main, master ]
 
+# Alte Läufe abbrechen, wenn ein neuer Push kommt (spart Zeit)
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
 jobs:
   build:
     runs-on: ubuntu-latest
@@ -27,7 +32,26 @@ jobs:
       - name: Build and test
         run: ./gradlew build --no-daemon --stacktrace
 
-  # Optional: run on Windows as well to catch OS-specific issues
+      - name: Publish Test Results
+        if: success() || failure()
+        uses: EnricoMi/publish-unit-test-result-action@v2
+        with:
+          files: build/test-results/**/*.xml
+          check_name: Test Results
+        continue-on-error: true
+
+  javadoc:
+    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
+          cache: gradle
+      - run: chmod +x gradlew && ./gradlew javadoc --no-daemon
+
   build-windows:
     runs-on: windows-latest
     steps: