Add runtime UV protection toggle and treat near-zero sense as external power.

Per-pod NVS enable (default off) via UART/ESP-NOW/dashboard, and skip UV latch when LiPo ADC reads ~0 mV so USB/external supply still boots.

Co-authored-by: Cursor <cursoragent@cursor.com>

main/powerpod.c

@@ -18,6 +18,7 @@
 #include "ota_confirm.h"
 #include "cmd_led_ring.h"
 #include "cmd_battery.h"
+#include "cmd_battery_uv.h"
 #include "cmd_set_log_level.h"
 #include "esp_now_comm.h"
 #include "powerpod.h"
@@ -233,6 +234,7 @@ void app_main(void) {
     cmd_client_id_map_reset_register();
     cmd_led_ring_register();
     cmd_battery_register();
+    cmd_battery_uv_register();
     cmd_ota_register();
     cmd_ota_slave_progress_register();
     cmd_set_log_level_register();