Remove the old in-cluster Stalwart

Its folder went in March (44c31cd) but the Argo CD app stayed and kept the
old hensen.io mail server running, with a NodePort for SMTP/IMAP and a
10Gi volume. Mail runs on node001 now and this one logged nothing in three
days. A final Velero backup (stalwart-final-202610220935) keeps its data
until 20 January 2027. The app has no finalizer, so the namespace gets
deleted by hand.

apps/templates/stalwart-folder.yaml

@@ -1,22 +0,0 @@
-apiVersion: argoproj.io/v1alpha1
-kind: Application
-metadata:
-  name: stalwart
-  namespace: argocd
-spec:
-  project: default
-  source:
-    repoURL: https://github.com/rubenhensen/k8scd.git
-    targetRevision: HEAD
-    path: stalwart
-  destination:
-    server: https://kubernetes.default.svc
-    namespace: stalwart
-  syncPolicy:
-    automated:
-      selfHeal: true
-      prune: true
-    syncOptions:
-    - CreateNamespace=true
-    automated:
-      selfHeal: true