feat(homarr): complete wiring for landing page deployment

Adds Homarr landing page with Authentik SSO:
- k8s/argocd/apps/60-applications.yaml: multi-source Application (homarr
  chart from homarr-labs + in-repo values), ns dashboard, wave 8
- k8s/bootstrap/ingress/ingress.yaml: homarr.riotpiao.com → dashboard/homarr:3000
- k8s/bootstrap/coredns/coredns-configmap.yaml: rewrite homarr.riotpiao.com
  to ingress controller
- k8s/security/iam/scripts/authentik-provision.py: added 'homarr' to SERVICES
  (generates OAuth provider/app + homarr-oidc secret with client-id/secret)
- k8s/security/iam/rbac-dashboard-rolebinding.yaml: grants authentik-provisioner
  SA access to dashboard ns for secret management
- k8s/security/iam/kustomization.yaml: includes new RoleBinding

Homarr now fully wired:
- Ingress: https://homarr.riotpiao.com
- SSO: redirects to Authentik, login as rock
- Persistence: 5Gi RWO on longhorn-wffc (3-replica HA)
- Tile config: UI-managed (saved to PVC)

k8s/security/iam/kustomization.yaml

@@ -14,6 +14,7 @@ kind: Kustomization
 resources:
   - key-rotation-cronjob.yaml
   - authentik-provision-job.yaml
+  - rbac-dashboard-rolebinding.yaml
 
 # Provisioning/verification python lives in scripts/*.py (real files, linted +
 # diff-friendly) and is generated into ConfigMaps here rather than embedded in