feat: Move cluster services to wild-directory as unified packages

Convert all 15 cluster services from embedded API format to
wild-directory packages using the unified manifest format:
- metallb, traefik, cert-manager, longhorn, snapshot-controller
- nfs, smtp, coredns, node-feature-discovery, nvidia-device-plugin
- externaldns, docker-registry, headlamp, crowdsec, utils

Changes:
- wild-manifest.yaml → manifest.yaml with is, defaultConfig, requires
- Eliminated configReferences and serviceConfig fields
- Flattened kustomize.template/ to package root
- Template vars use flat defaultConfig keys
- install.sh paths updated for apps/ layout
- Updated 9 app manifests: cloud.smtp.* → apps.smtp.* with requires
- Removed dead install: true field from 6 app manifests

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

headlamp/kubeconfig-cm.yaml

@@ -0,0 +1,24 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: headlamp-kubeconfig
+  namespace: headlamp
+data:
+  kubeconfig: |
+    apiVersion: v1
+    kind: Config
+    clusters:
+    - cluster:
+        certificate-authority: /var/run/secrets/kubernetes.io/serviceaccount/ca.crt
+        server: https://kubernetes.default.svc
+      name: in-cluster
+    contexts:
+    - context:
+        cluster: in-cluster
+        user: headlamp-admin
+      name: in-cluster
+    current-context: in-cluster
+    users:
+    - name: headlamp-admin
+      user:
+        tokenFile: /var/run/secrets/kubernetes.io/serviceaccount/token