There was a complication when using the unit on the field and changing WiFi behavior: the client option would look for the registered network and hung for some time.
Since WiFi client (wifi_sta in the code) is only needed at home when setting things up or uploading software, but not at all on the field, the behavior of the BOOT button is now
- short press: switch between WiFi in Access Point mode or WiFi off
- long press: enable WiFi client mode