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>

snapshot-controller/deployment.yaml

@@ -0,0 +1,36 @@
+---
+kind: Deployment
+apiVersion: apps/v1
+metadata:
+  name: snapshot-controller
+  namespace: kube-system
+spec:
+  replicas: 2
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: snapshot-controller
+  minReadySeconds: 35
+  strategy:
+    rollingUpdate:
+      maxSurge: 0
+      maxUnavailable: 1
+    type: RollingUpdate
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: snapshot-controller
+    spec:
+      serviceAccountName: snapshot-controller
+      containers:
+        - name: snapshot-controller
+          image: registry.k8s.io/sig-storage/snapshot-controller:v8.1.0
+          args:
+            - "--v=5"
+            - "--leader-election=true"
+          imagePullPolicy: IfNotPresent
+          resources:
+            limits:
+              memory: 300Mi
+            requests:
+              cpu: 10m
+              memory: 20Mi