feat(db): add battery field

Signed-off-by: Klagarge <remi@heredero.ch>

db/src/main.go

@@ -23,6 +23,7 @@ type ProvenceData struct {
 	CO2PPM   int     `json:"co2_ppm"`
 	Temp     float64 `json:"temp"`
 	Humidity int     `json:"humidity"`
+	Battery  int     `json:"battery"`
 	Window   bool    `json:"window"`
 }
 
@@ -135,7 +136,8 @@ func main() {
 			return
 		}
 
-		log.Printf("[Main] Received gateway=%s node=%s -> campus=%s room=%s\n", gatewayID, nodeID, campus, room)
+		batteryLevel := dp.GetValues().Battery
+		log.Printf("[Main] Received gateway=%s node=%s -> campus=%s room=%s (Battery %d%%)\n", gatewayID, nodeID, campus, room, batteryLevel)
 
 		// Re-create the datapoint with campus/room tags for Influx
 		influxTags := []point.Topic{