config, ui: add JSON output format support

config/format.go

+package config
+
+import "github.com/urfave/cli/v3"
+
+const (
+	FormatText = "text"
+	FormatJSON = "json"
+)
+
+var FormatFlag = &cli.StringFlag{
+	Name:    "format",
+	Usage:   "output format (text, json)",
+	Value:   FormatText,
+	Aliases: []string{"o"},
+}
+
+func IsJSON(cmd *cli.Command) bool {
+	return cmd.String("format") == FormatJSON
+}

ui/json.go

+package ui
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+type JSONItem struct {
+	Name        string `json:"name"`
+	Status      string `json:"status,omitempty"`
+	Description string `json:"description,omitempty"`
+	Value       string `json:"value,omitempty"`
+}
+
+func TreeItemsToJSON(items []TreeItem) []JSONItem {
+	result := make([]JSONItem, len(items))
+	for i, item := range items {
+		result[i] = JSONItem{
+			Name:        item.Name,
+			Status:      item.Status.Label,
+			Description: item.Description,
+		}
+	}
+	return result
+}
+
+func PrintJSON(data interface{}) error {
+	output, err := json.MarshalIndent(data, "", "  ")
+	if err != nil {
+		return err
+	}
+	fmt.Println(string(output))
+	return nil
+}