feat(childManage): add WeekDay enum for day tracking

src/main/java/com/marketingconfort/brainboost_common/childManage/enums/WeekDay.java

+package com.marketingconfort.brainboost_common.childManage.enums;
+
+public enum WeekDay {
+    LUN, MAR, MER, JEU, VEN, SAM, DIM
+}