Yearlong Dragon Boss - 8000 HP balanced-damage edition for Minecraft Java 1.21.1

Design target:
- ~8,000 effective HP.
- Keep special-attack frequency high.
- Lower individual hit damage so enchanted Diamond is viable.
- Still deal noticeable damage through fully enchanted Netherite.
- Preserve breath, fireballs, lightning, phase escalation, and custom bossbar.

Install:
1. Remove/disable the older Yearlong Dragon Boss datapack.
2. Put this ZIP directly in <world>/datapacks/
3. Restart the server or run /reload
4. Run /datapack list

Approximate bonus damage before armor:
Phase I close aura: 14 damage = 7 hearts
Phase II close aura: 18 damage = 9 hearts
Final phases close aura: 22 damage = 11 hearts
Breath: 2 / 3 / 4 hearts of magic damage
Outer aura: 2.5 / 3.5 / 4.5 hearts

Minecraft caps normal max health near 1024, so the ~8,000 HP pool is simulated with hidden health phases.
