[Feature Request]: App configurable deep sleep voltage

[Dude5101]

Platform

ESP32

Description

Heltec V3 and other Heltec boards become unstable when battery voltage drops below 3.3v
Current firmware goes into deep sleep when voltage is less than 3.1v which causes boot loop/brownout issues on Heltec boards.

Please add an option to change deep sleep voltage to a user-configurable value.

Current workaround I am using is to adjust ADC override down to 4.6 on Heltec boards, deep sleep then kicks in at 3.3v as measured at battery terminals and shows 3.09v on meshtastic app. Obviously battery level is then wrong and never reaches 4.2v in the app.