feat: App-Version aus pom.xml im Header anzeigen

- Versionsnummer neben "Workflow Editor" in Klammern und kleinerer Schrift
- tasklist.app-version per Maven-Resource-Filtering (@project.version@) gefüllt
- @Value-Injection in MainView; Anzeige nur bei real gefülltem Wert

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/main/java/de/assecutor/tasklisteditor/view/MainView.java

@@ -46,6 +46,7 @@ import elemental.json.JsonArray;
 import elemental.json.JsonObject;
 
 import com.fasterxml.jackson.databind.JsonNode;
+import org.springframework.beans.factory.annotation.Value;
 
 import java.time.ZoneId;
 import java.time.format.DateTimeFormatter;
@@ -79,6 +80,7 @@ public class MainView extends VerticalLayout implements BeforeEnterObserver {
     private final Map<Integer, BlockInstance> instances = new HashMap<>();
     private Div palettePanel;
     private String currentListName;
+    private final String appVersion;
 
     public MainView(BlockTypeRegistry registry,
                     TaskListService taskListService,
@@ -87,7 +89,9 @@ public class MainView extends VerticalLayout implements BeforeEnterObserver {
                     CanvasService canvasService,
                     CustomTypeService customTypeService,
                     ElementSettingsService elementSettingsService,
-                    ObjectMapper objectMapper) {
+                    ObjectMapper objectMapper,
+                    @Value("${tasklist.app-version:}") String appVersion) {
+        this.appVersion = appVersion;
         this.registry = registry;
         this.taskListService = taskListService;
         this.taskListImporter = taskListImporter;
@@ -146,6 +150,15 @@ public class MainView extends VerticalLayout implements BeforeEnterObserver {
         title.addClassName("tasklist-title");
         title.getStyle().set("white-space", "nowrap");
 
+        if (appVersion != null && !appVersion.isBlank() && !appVersion.startsWith("@")) {
+            Span version = new Span(" (v" + appVersion + ")");
+            version.getStyle()
+                    .set("font-size", "0.7em")
+                    .set("color", "var(--lumo-secondary-text-color)")
+                    .set("white-space", "nowrap");
+            title.add(version);
+        }
+
         Button clear = new Button("Workflow löschen", new Icon(VaadinIcon.TRASH));
         clear.addThemeVariants(ButtonVariant.LUMO_TERTIARY);
         clear.addClickListener(e -> {

src/main/resources/application.properties

@@ -1,5 +1,9 @@
 server.port=8080
 
+# Anwendungsversion: wird beim Build per Maven-Resource-Filtering
+# (spring-boot-starter-parent, @...@-Delimiter) aus der pom.xml gefüllt.
+tasklist.app-version=@project.version@
+
 vaadin.launch-browser=true
 vaadin.allowed-packages=de.assecutor.tasklisteditor