feat(k3s): replace nginx loadbalancer with kube-vip for control-plane HA

Deploys kube-vip as a DaemonSet on all k3s server nodes, advertising a
VIP (192.168.20.2) via ARP. Eliminates the single-point-of-failure
k3s-loadbalancer VM.

- New kube_vip role: RBAC + DaemonSet templates, TLS SAN cert rotation
- playbooks/kube-vip.yaml: migration playbook (serial=1, idempotent)
- Updated k3s install tasks (server primary/secondary, agent) to use k3s_vip
  instead of the loadbalancer VM IP
- Added k3s_vip: 192.168.20.2 to group_vars (below DHCP range .11-.250)

Migration steps in playbook header comment.

roles/kube_vip/templates/kube-vip-rbac.yaml.j2

@@ -0,0 +1,44 @@
+apiVersion: v1
+kind: ServiceAccount
+metadata:
+  name: kube-vip
+  namespace: kube-system
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+  annotations:
+    rbac.authorization.kubernetes.io/autoupdate: "true"
+  name: system:kube-vip-role
+rules:
+  - apiGroups: [""]
+    resources: ["services/status"]
+    verbs: ["update"]
+  - apiGroups: [""]
+    resources: ["services", "endpoints"]
+    verbs: ["list", "get", "watch", "update"]
+  - apiGroups: [""]
+    resources: ["nodes"]
+    verbs: ["list", "get", "watch", "update", "patch"]
+  - apiGroups: ["coordination.k8s.io"]
+    resources: ["leases"]
+    verbs: ["list", "get", "watch", "update", "create"]
+  - apiGroups: ["discovery.k8s.io"]
+    resources: ["endpointslices"]
+    verbs: ["list", "get", "watch", "update"]
+  - apiGroups: [""]
+    resources: ["pods"]
+    verbs: ["list"]
+---
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+  name: system:kube-vip-binding
+roleRef:
+  apiGroup: rbac.authorization.k8s.io
+  kind: ClusterRole
+  name: system:kube-vip-role
+subjects:
+- kind: ServiceAccount
+  name: kube-vip
+  namespace: kube-system