feat: add ax serve command with JSON API backed by NodeService

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

cmd/serve.go

@@ -0,0 +1,30 @@
+package cmd
+
+import (
+	"axolotl/serve"
+	"axolotl/service"
+	"fmt"
+	"net/http"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+var serveCmd = &cobra.Command{
+	Use:   "serve",
+	Short: "Start the JSON API server",
+	Run: func(cmd *cobra.Command, args []string) {
+		sc := cfg.GetServerConfig()
+		addr := fmt.Sprintf("%s:%d", sc.Host, sc.Port)
+		handler := serve.New(service.GetNodeServiceForUser)
+		fmt.Fprintf(os.Stdout, "listening on %s\n", addr)
+		if err := http.ListenAndServe(addr, handler); err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
+	},
+}
+
+func init() {
+	rootCmd.AddCommand(serveCmd)
+}