Battery status reporting in software

[jwoglom]

Hi Zitao, really awesome work on this cyberdeck. It is such a cool device. I was wondering whether there is any ability in the current design of the Hackberry Pi to view the battery status level in software, sent in some way via the GPIO pins? The battery status lights on the bottom of the case are nice for a general indication of how much capacity is available but I could imagine it being useful to do things like automatically turn the device off safely or dim screen brightness if battery is low. Totally fine if the current design doesn't accommodate this, but could be a nice addition for a theoretical V2 product.