feat: allow restrict Pomodoro via password

- introduce password flag in server command line options
- update clientCommand model
- add password requirement for controlling the Pomodoro timer
- document password in README

cmd/server/main.go

@@ -14,12 +14,14 @@ func Start() {
 	// Define CLI flags for ListenAddress and ListenPort
 	listenAddress := flag.String("listenAddress", shared.DefaultServerConfig.ListenAddress, "IP address to listen on")
 	listenPort := flag.Int("listenPort", shared.DefaultServerConfig.ListenPort, "Port to listen on")
+	password := flag.String("password", "", "Control password for pomodoro session (optional)")
 	flag.Parse()
 
 	serverConfig := models.GoTomatoServerConfig{
 		ListenAddress: *listenAddress,
 		ListenPort:    *listenPort,
 	}
+	shared.PomodoroPassword = *password
 
 	listen := fmt.Sprintf("%s:%d", serverConfig.ListenAddress, serverConfig.ListenPort)