ax(node): rename Worker.node field to nodeManager for AX Principle 1 compliance

The field `node *NodeManager` used an ambiguous single-word name that required
context to understand. Renamed to `nodeManager` to be self-describing per AX
Principle 1: predictable names over short names.

Co-Authored-By: Charon <charon@lethean.io>

pkg/node/worker.go

@@ -44,7 +44,7 @@ type ProfileManager interface {
 // worker.SetProfileManager(profileManager)
 // worker.RegisterWithTransport() // begin processing incoming messages
 type Worker struct {
-	node           *NodeManager
+	nodeManager    *NodeManager
 	transport      *Transport
 	minerManager   MinerManager
 	profileManager ProfileManager
@@ -56,9 +56,9 @@ type Worker struct {
 // worker.RegisterWithTransport()
 func NewWorker(node *NodeManager, transport *Transport) *Worker {
 	return &Worker{
-		node:      node,
-		transport: transport,
-		startTime: time.Now(),
+		nodeManager: node,
+		transport:   transport,
+		startTime:   time.Now(),
 	}
 }
 
@@ -98,7 +98,7 @@ func (worker *Worker) HandleMessage(conn *PeerConnection, msg *Message) {
 
 	if err != nil {
 		// Send error response
-		identity := worker.node.GetIdentity()
+		identity := worker.nodeManager.GetIdentity()
 		if identity != nil {
 			errorMessage, _ := NewErrorMessage(
 				identity.ID,
@@ -139,7 +139,7 @@ func (worker *Worker) handlePing(msg *Message) (*Message, error) {
 
 // response, err := worker.handleGetStats(message)
 func (worker *Worker) handleGetStats(msg *Message) (*Message, error) {
-	identity := worker.node.GetIdentity()
+	identity := worker.nodeManager.GetIdentity()
 	if identity == nil {
 		return nil, &ProtocolError{Code: ErrCodeUnauthorized, Message: "node identity not initialized"}
 	}