fix: also push :latest tag on every build

values.yaml image.tag defaults to 'latest' for initial deploy.
Pipeline always pushes both <branch>-<random8> and :latest so
ArgoCD can pull the newest image without a chart version bump.

vars/dockerBuildPush.groovy

@@ -34,6 +34,8 @@ def call(Map config) {
             docker login ${registry} -u \${HARBOR_USER} -p \${HARBOR_PASS}
             docker build -f ${dockerfile} -t ${fullImage}:${tag} ${context}
             docker push ${fullImage}:${tag}
+            docker tag ${fullImage}:${tag} ${fullImage}:latest
+            docker push ${fullImage}:latest
         """
     }