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/README.md

@@ -0,0 +1,49 @@
+# Snapshot Controller
+
+The snapshot controller is a Kubernetes component that manages the lifecycle of volume snapshots. It works in conjunction with CSI drivers to enable backup and restore functionality for persistent volumes.
+
+## Architecture
+
+The snapshot functionality in Kubernetes is split into two components:
+- **Snapshot Controller** (this service): Cluster-wide controller that manages VolumeSnapshot resources
+- **CSI Snapshotter Sidecar**: Deployed with each CSI driver (e.g., Longhorn) to perform actual snapshot operations
+
+## Installation
+
+This service is installed automatically by Wild Cloud when setting up cluster services. It deploys:
+- The snapshot-controller deployment (2 replicas with leader election)
+- Required RBAC permissions
+- VolumeSnapshot CRDs (if not already present)
+
+## Dependencies
+
+- Requires a CSI driver with snapshot support (e.g., Longhorn)
+- Requires VolumeSnapshot CRDs (included with this service)
+
+## Verification
+
+After installation, verify the controller is running:
+```bash
+kubectl get pods -n kube-system | grep snapshot-controller
+kubectl api-resources | grep snapshot
+```
+
+## Usage
+
+Once installed, you can create VolumeSnapshots for any PVC managed by a CSI driver:
+```yaml
+apiVersion: snapshot.storage.k8s.io/v1
+kind: VolumeSnapshot
+metadata:
+  name: my-snapshot
+  namespace: default
+spec:
+  volumeSnapshotClassName: longhorn-snapshot-class
+  source:
+    persistentVolumeClaimName: my-pvc
+```
+
+## References
+
+- [Kubernetes CSI Snapshot Documentation](https://kubernetes-csi.github.io/docs/snapshot-restore-feature.html)
+- [External Snapshotter GitHub](https://github.com/kubernetes-csi/external-snapshotter)