feat(power): add configurable auto-poweroff from deep sleep

[dysprosium]

• add a configurable Auto poweroff timeout for deep sleep, defaulting to Off
• arm the RTC wake alarm only when enabled, then route expiry through the existing safe shutdown path
• preserve MinArch SRAM/RTC/quicksave data and only create the auto-resume marker when state serialization succeeds
• support TG5040, TG5050, and H700, including shutdown while an H700 clamshell remains closed

Tested on the RG SP
Todo: test on TrimUI devices

[iijaachok]

Thanks, hopefully this will be merged into main! I've been running the deep sleep tracking script from this repo and it seems that H700 doesn't quite reach the battery drain efficiency like TrimUI etc.

On Anbernic RG SP with a deep sleep battery will drain eventually over 60-100 hours in deep sleep, based on the log's projections.