Aetherbound RPG - DarkTimer 30 Minutes

This datapack overrides DarkTimer's messages and timer for Minecraft 1.21.1.

Timer:
- Initial warning: 30 minutes
- 1-minute warning
- 10-second warning
- Dropped items are then cleared

The 30-minute cycle uses 1740s in darktimerwarn10.mcfunction because DarkTimer adds its 1-minute base countdown afterward.

Translation keys expected from KubeJS/resource assets:
- aetherbound.darktimer.warn30
- aetherbound.darktimer.warn1
- aetherbound.darktimer.warn10s
- aetherbound.darktimer.clear
