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.yaml.j2

@@ -0,0 +1,81 @@
+apiVersion: apps/v1
+kind: DaemonSet
+metadata:
+  labels:
+    app.kubernetes.io/name: kube-vip-ds
+    app.kubernetes.io/version: {{ kube_vip_version }}
+  name: kube-vip-ds
+  namespace: kube-system
+spec:
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: kube-vip-ds
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: kube-vip-ds
+        app.kubernetes.io/version: {{ kube_vip_version }}
+    spec:
+      affinity:
+        nodeAffinity:
+          requiredDuringSchedulingIgnoredDuringExecution:
+            nodeSelectorTerms:
+            - matchExpressions:
+              - key: node-role.kubernetes.io/master
+                operator: Exists
+            - matchExpressions:
+              - key: node-role.kubernetes.io/control-plane
+                operator: Exists
+      containers:
+      - name: kube-vip
+        image: ghcr.io/kube-vip/kube-vip:{{ kube_vip_version }}
+        imagePullPolicy: IfNotPresent
+        args:
+        - manager
+        env:
+        - name: vip_arp
+          value: "true"
+        - name: port
+          value: "6443"
+        - name: vip_nodename
+          valueFrom:
+            fieldRef:
+              fieldPath: spec.nodeName
+        - name: vip_interface
+          value: "{{ kube_vip_interface }}"
+        - name: vip_cidr
+          value: "32"
+        - name: dns_mode
+          value: first
+        - name: cp_enable
+          value: "true"
+        - name: cp_namespace
+          value: kube-system
+        - name: svc_enable
+          value: "false"
+        - name: vip_leaderelection
+          value: "true"
+        - name: vip_leasename
+          value: plndr-cp-lock
+        - name: vip_leaseduration
+          value: "5"
+        - name: vip_renewdeadline
+          value: "3"
+        - name: vip_retryperiod
+          value: "1"
+        - name: address
+          value: "{{ k3s_vip }}"
+        - name: prometheus_server
+          value: :2112
+        securityContext:
+          capabilities:
+            add:
+            - NET_ADMIN
+            - NET_RAW
+      hostNetwork: true
+      serviceAccountName: kube-vip
+      tolerations:
+      - effect: NoSchedule
+        operator: Exists
+      - effect: NoExecute
+        operator: Exists