feat: The Dream Courts: unify death events & mechanics

[jprzimba]

This PR will be merged only people test and share results

• Centralize and extend Dream Courts mechanics: add DreamScar and DreamScarGlobal storages.
• Replace per-boss CreatureEvent "DreamCourtsBossDeath" with a unified "dreamCourtsDeath" handler (new creaturescripts_dream_courts_death.lua) that sets player storages, arena timers, awards outfits, spawns attendants->abominations, and tracks Alptramun summons; remove the old actions_bosses_killed.lua.
• Add movements_corrupted_nature.lua to transform Plant Attendant into Plant Abomination and heal Plagueroot on specific step-in.
• Update bosses to register the new death event and add facelessBaneImmunity event; add faceless bane onSpawn logic to initialize storages and reward flag.
• Tweak facelessBaneImmunity to require 3 deaths before reset and to block incoming damage when immunity triggers.