OCPEDGE-2416: Add oc adm transition topology command

Implement SNO to HA topology transition command with comprehensive
preflight validation, user confirmation prompts, and status monitoring.

Features:
- Three operational modes: discovery, initiate, status
- Tiered preflight validation (Error and Warning severity checks)
- Client-side feature gate (OC_ENABLE_CMD_TRANSITION_TOPOLOGY)
- Server-side validation (MutableTopology feature gate check)
- User confirmation with bypass support (--allow-transition-with-warnings)

Preflight checks (10 total):
- Error-severity (blocking): Supported transition, feature gate enabled
- Warning-severity (bypassable): Cluster operators stable, control plane
  node count/schedulability/readiness, etcd quorum/stability/voting members

Implementation structure:
- pkg/cli/admin/transition/transition.go: Main command and orchestration
- pkg/cli/admin/transition/status.go: Status monitoring subcommand
- pkg/cli/admin/transition/preflight/: Validation logic and types
- pkg/cli/admin/transition/prompt/: User interaction and confirmation

Command is gated behind OC_ENABLE_CMD_TRANSITION_TOPOLOGY environment
variable and only appears in cluster management commands when enabled.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: jaypoulz

pkg/cli/admin/admin.go

@@ -35,6 +35,7 @@ import (
 	"github.com/openshift/oc/pkg/cli/admin/release"
 	"github.com/openshift/oc/pkg/cli/admin/restartkubelet"
 	"github.com/openshift/oc/pkg/cli/admin/top"
+	"github.com/openshift/oc/pkg/cli/admin/transition"
 	"github.com/openshift/oc/pkg/cli/admin/upgrade"
 	"github.com/openshift/oc/pkg/cli/admin/verifyimagesignature"
 	"github.com/openshift/oc/pkg/cli/admin/waitfornodereboot"
@@ -50,6 +51,9 @@ var adminLong = ktemplates.LongDesc(`
 // inspectAlertsFeatureGate is an environment variable used to gate the inclusion of the inspect-alerts subcommand.
 const inspectAlertsFeatureGate = "OC_ENABLE_CMD_INSPECT_ALERTS"
 
+// transitionTopologyFeatureGate is an environment variable used to gate the inclusion of the transition topology subcommand.
+const transitionTopologyFeatureGate = "OC_ENABLE_CMD_TRANSITION_TOPOLOGY"
+
 func NewCommandAdmin(f kcmdutil.Factory, streams genericiooptions.IOStreams) *cobra.Command {
 	// Main command
 	cmds := &cobra.Command{
@@ -72,6 +76,10 @@ func NewCommandAdmin(f kcmdutil.Factory, streams genericiooptions.IOStreams) *co
 		clusterManagement = append(clusterManagement, inspectalerts.New(f, streams))
 	}
 
+	if kcmdutil.FeatureGate(transitionTopologyFeatureGate).IsEnabled() {
+		clusterManagement = append(clusterManagement, transition.NewCmdTransition(f, streams))
+	}
+
 	groups := ktemplates.CommandGroups{
 		{
 			Message:  "Cluster Management:",

pkg/cli/admin/transition/constants.go

@@ -0,0 +1,38 @@
+package transition
+
+import (
+	configv1 "github.com/openshift/api/config/v1"
+)
+
+// Kubernetes and OpenShift resource names
+const (
+	// InfrastructureResourceName is the name of the cluster-scoped Infrastructure resource
+	InfrastructureResourceName = "cluster"
+
+	// EtcdOperatorResourceName is the name of the cluster-scoped Etcd operator resource
+	EtcdOperatorResourceName = "cluster"
+
+	// EtcdNamespace is the namespace where etcd resources are located
+	EtcdNamespace = "openshift-etcd"
+
+	// EtcdEndpointsConfigMapName is the name of the ConfigMap containing etcd endpoints
+	EtcdEndpointsConfigMapName = "etcd-endpoints"
+)
+
+// ClusterOperator condition types
+const (
+	// ClusterOperatorAvailable indicates the operand is available
+	ClusterOperatorAvailable configv1.ClusterStatusConditionType = configv1.OperatorAvailable
+
+	// ClusterOperatorProgressing indicates the operand is being updated
+	ClusterOperatorProgressing configv1.ClusterStatusConditionType = configv1.OperatorProgressing
+
+	// ClusterOperatorDegraded indicates the operand is degraded
+	ClusterOperatorDegraded configv1.ClusterStatusConditionType = configv1.OperatorDegraded
+)
+
+// Etcd operator condition types
+const (
+	// EtcdMembersAvailableCondition indicates etcd has quorum
+	EtcdMembersAvailableCondition = "EtcdMembersAvailable"
+)