refactor: Kubernetes-Ressourcen und Images heissen artista-modelcamp

Alle Ressourcen tragen den Praefix artista-modelcamp- im Namespace
artista; Images <owner>/artista-modelcamp und
<owner>/artista-modelcamp-tools. DATABASE_URL-Host, Backup-Host,
Traefik-Middleware-Referenz und Betriebsdoku entsprechend angepasst.

Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>

k8s/base/kustomization.yaml

@@ -10,5 +10,5 @@ resources:
   - jobs.yaml
 labels:
   - pairs:
-      app.kubernetes.io/part-of: artista-filmcamp
+      app.kubernetes.io/part-of: artista-modelcamp
     includeSelectors: false