fix(go): use hasChildrenHint JSON key for browse parity; warn on -parent 0

Rename the browse JSON key from hasChildren to hasChildrenHint to match the
Rust and Python CLIs and the library property name (HasChildrenHint). Update
the text-output label to match. Add a one-line stderr warning when -parent 0
is supplied, since 0 is the server root sentinel and omitting -parent is the
intended way to walk from the root.

clients/go/cmd/mxgw-go/main.go

@@ -1568,6 +1568,9 @@ func runGalaxyBrowse(ctx context.Context, args []string, stdout, stderr io.Write
 
 	// A specific parent → one level of children via the raw parent-scoped RPC.
 	if *parent >= 0 {
+		if *parent == 0 {
+			fmt.Fprintln(stderr, "warning: -parent 0 is the server root sentinel; omit -parent for the root walk, or use -parent <id> >= 1")
+		}
 		if *depth > 0 {
 			fmt.Fprintln(stderr, "warning: -depth is ignored when -parent is specified")
 		}
@@ -1696,7 +1699,7 @@ func expandToDepth(ctx context.Context, node *mxgateway.LazyBrowseNode, remainin
 func printLazyNode(stdout io.Writer, node *mxgateway.LazyBrowseNode, level int) {
 	indent := strings.Repeat("  ", level)
 	obj := node.Object()
-	fmt.Fprintf(stdout, "%s%d\t%s\t%s\t(attrs=%d, hasChildren=%t)\n",
+	fmt.Fprintf(stdout, "%s%d\t%s\t%s\t(attrs=%d, hasChildrenHint=%t)\n",
 		indent, obj.GetGobjectId(), obj.GetTagName(), obj.GetBrowseName(), len(obj.GetAttributes()), node.HasChildrenHint())
 	for _, child := range node.Children() {
 		printLazyNode(stdout, child, level+1)
@@ -1707,7 +1710,7 @@ func printLazyNode(stdout io.Writer, node *mxgateway.LazyBrowseNode, level int)
 // nested JSON object.
 func lazyNodeToJSON(node *mxgateway.LazyBrowseNode) map[string]any {
 	out := galaxyObjectToJSON(node.Object())
-	out["hasChildren"] = node.HasChildrenHint()
+	out["hasChildrenHint"] = node.HasChildrenHint()
 	children := node.Children()
 	jsonChildren := make([]map[string]any, 0, len(children))
 	for _, child := range children {