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>

goTool/cmd_battery_uv.go

@@ -0,0 +1,34 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+
+	"powerpod/gotool/pb"
+)
+
+func runBatteryUv(sp *serialPort, args []string) error {
+	fs := flag.NewFlagSet("battery-uv", flag.ExitOnError)
+	write := fs.Bool("set", false, "write UV protection enable (default: read)")
+	enabled := fs.Bool("enable", false, "enable software UV protection")
+	clientID := fs.Uint("client", 0, "client id (0=local master)")
+	all := fs.Bool("all", false, "apply to master + all registered slaves")
+	if err := fs.Parse(args); err != nil {
+		return err
+	}
+
+	r, err := sp.batteryUv(&pb.BatteryUvRequest{
+		Write:      *write,
+		Enabled:    *enabled,
+		ClientId:   uint32(*clientID),
+		AllClients: *all,
+	})
+	if err != nil {
+		return err
+	}
+
+	fmt.Printf("client_id=%d success=%v enabled=%v latched=%v slaves_updated=%d\n",
+		r.GetClientId(), r.GetSuccess(), r.GetEnabled(), r.GetLatched(),
+		r.GetSlavesUpdated())
+	return nil
+}