Add EndCommand and DimensionScheduleText for improved End dimension management and messaging

common/src/main/resources/dimension-schedule.yml

@@ -3,6 +3,7 @@
 times:
   end-open-at: "2026-11-08T19:16:34+01:00"
   outer-end-open-at: null
+  nether-open-at: null
 
 messages:
   end-activation-denied: