Detect under-voltage on GPIO1/11, persist UV state in NVS, enter a minimal
power mode without ESP-NOW, and recover after charge; expose LED mode 6
battery-low for host testing via goTool.
Co-authored-by: Cursor <cursoragent@cursor.com>
Each node saves its local deadzone on UART or ESP-NOW set; pod_settings loads and applies it after BMA456 init.
Co-authored-by: Cursor <cursoragent@cursor.com>