argocd: add Image Updater for auto-deploy on image push

- Install argocd-image-updater via Helm (wave 1)
- Configure Forgejo registry (anonymous pulls)
- Annotate apps for auto-update: api-gw, portfolio, management-service, queue-crd
- Uses newest-build strategy for commit SHA tags

k8s/argocd/apps/60-applications.yaml

@@ -246,6 +246,10 @@ metadata:
   namespace: argocd
   annotations:
     argocd.argoproj.io/sync-wave: "8"
+    # ArgoCD Image Updater - auto-update on new image push
+    argocd-image-updater.argoproj.io/image-list: app=forgejo.riotpiao.com/rock/portfolio
+    argocd-image-updater.argoproj.io/app.update-strategy: newest-build
+    argocd-image-updater.argoproj.io/write-back-method: argocd
 spec:
   project: homelab
   source: