Deploy Prowler CIS scanner (#310)

## Summary
- Deploy Prowler 5 as a weekly CronJob on minikube-indri for CIS Kubernetes Benchmark v1.11 scanning
- Custom slim container build (strips PowerShell, Trivy, and non-K8s providers from upstream)
- Reports (HTML, CSV, JSON-OCSF) written to NFS share on sifaka at `/volume1/reports/prowler/`
- Read-only ClusterRole for pod, RBAC, and control plane inspection
- Host path mounts + hostPID for kubelet file permission checks

## Follow-ups
- Mirror prowler-cloud/prowler on forge for supply chain control
- Build and push container image, update kustomization.yaml newTag
- Consider adding k3s-ringtail scanning (core + RBAC checks only)

## Test plan
- [ ] Build container: `mise run container-release prowler v5.22.0`
- [ ] Update `argocd/manifests/prowler/kustomization.yaml` newTag to built image tag
- [ ] Sync ArgoCD: `argocd app sync apps && argocd app set prowler --revision deploy-prowler && argocd app sync prowler`
- [ ] Trigger manual job: `kubectl create job --from=cronjob/prowler prowler-manual -n prowler --context=minikube-indri`
- [ ] Verify reports appear on sifaka NFS share
- [ ] `mise run services-check`

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: #310

docs/changelog.d/deploy-prowler.feature.md

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+Deploy Prowler CIS scanner as a weekly CronJob on minikube-indri, with reports written to sifaka NFS share.