feat(kubernetes): Add Kubernetes mock data and UI

Backend:
- Add K8s cluster, node, pod, deployment mock data generation
- Configurable via PULSE_MOCK_K8S_CLUSTERS, PULSE_MOCK_K8S_NODES,
  PULSE_MOCK_K8S_PODS, PULSE_MOCK_K8S_DEPLOYMENTS env vars
- Generate realistic cluster data with versions, namespaces, pod phases
- Add dynamic metric updates for K8s resources
- Deep copy K8s data in cloneState to prevent race conditions

Frontend:
- Add KubernetesClusters component with 4 view modes:
  Clusters, Nodes, Pods, Deployments
- Filter bar with search, status filter, show hidden toggle
- Nodes view: status, roles, CPU/memory/pod capacity, kubelet version
- Pods view: namespace, status, ready containers, restarts, image, age
- Deployments view: replicas, ready/up-to-date status
- Matches Docker/Dashboard table styling patterns

mock.env

@@ -2,5 +2,12 @@ PULSE_MOCK_MODE=false
 PULSE_MOCK_NODES=7
 PULSE_MOCK_VMS_PER_NODE=5
 PULSE_MOCK_LXCS_PER_NODE=8
+PULSE_MOCK_DOCKER_HOSTS=3
+PULSE_MOCK_DOCKER_CONTAINERS=12
+PULSE_MOCK_GENERIC_HOSTS=4
+PULSE_MOCK_K8S_CLUSTERS=2
+PULSE_MOCK_K8S_NODES=4
+PULSE_MOCK_K8S_PODS=30
+PULSE_MOCK_K8S_DEPLOYMENTS=12
 PULSE_MOCK_RANDOM_METRICS=true
 PULSE_MOCK_STOPPED_PERCENT=20