Add Argo CD Application for stack.basicstack.de GitOps management

Creates the Argo CD Application that manages all cluster infrastructure
applications from the stack.basicstack.de repository. Configuration:
- Points to cluster-internal Forgejo (forgejo.forgejo.svc.cluster.local)
- Excludes argocd directory to prevent self-management
- Enables selfHeal for automatic sync of changes
- Disables prune for manual deletion approval
- Deployed to the cluster and verified working

All existing services (Stalwart, Directus, Forgejo, BookStack, Pocket ID,
OpenCloud, Passbolt) remain operational. Some pods restarted due to applying
pending git changes (expected GitOps behavior).

Note: Warning about duplicate opencloud namespace definition in
openldap-deployment.yaml and opencloud-deployment.yaml - does not affect
functionality, can be addressed in follow-up cleanup.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/argocd/app-stack-basicstack-de.yaml

@@ -0,0 +1,23 @@
+apiVersion: argoproj.io/v1alpha1
+kind: Application
+metadata:
+  name: stack-basicstack-de
+  namespace: argocd
+spec:
+  project: default
+  source:
+    repoURL: git@forgejo.forgejo.svc.cluster.local:basicstack/stack.basicstack.de.git
+    targetRevision: main
+    path: apps
+    directory:
+      recurse: true
+      exclude: |
+        **/argocd/**
+  destination:
+    server: https://kubernetes.default.svc
+  syncPolicy:
+    automated:
+      prune: false  # Manual approval for deletions
+      selfHeal: true
+    syncOptions:
+    - CreateNamespace=true