Add spare-power-meter esphome config

Avoid forgetting to reflash it with latest config.

reflash.sh

@@ -39,6 +39,7 @@ for config in \
 		zigbee-coordinator-ch25.yaml \
 		child-west-ac.yaml \
 		child-east-ac.yaml \
+		spare-power-meter.yaml \
 		tools-power.yaml; do
 	flash+=("${command?} ${config?}")
 done

spare-power-meter.yaml

@@ -0,0 +1,2 @@
+packages:
+  device_base: !include templates/mystrom.yaml