fix(discovery): improve MQTT discovery for scene CC (#3539)

Co-authored-by: Daniel Lando <daniel.sorridi@gmail.com>

api/lib/Gateway.ts

@@ -1314,7 +1314,9 @@ export default class Gateway {
 					} else return
 					break
 				case CommandClasses['Central Scene']:
-				case CommandClasses['Scene Activation']:
+					if (!valueId.readable || valueId.writeable) {
+						return
+					}
 					cfg = utils.copy(hassCfg.central_scene)
 
 					// Combile unique Object id, by using all possible scenarios
@@ -1323,6 +1325,9 @@ export default class Gateway {
 						valueId.property,
 						valueId.propertyKey,
 					)
+					if (valueId.type === 'number') {
+						cfg.discovery_payload.state_class = 'measurement'
+					}
 					break
 				case CommandClasses['Binary Sensor']: {
 					// https://github.com/zwave-js/node-zwave-js/blob/master/packages/zwave-js/src/lib/commandclass/BinarySensorCC.ts#L41