Vincible

Bug fix — power stacking: upgradeToHighClass now calls removeViltrumite before registering High Class, and upgradeToGrandRegent now calls removeHighClass + removeViltrumite before registering Grand Regent. All three tiers' powers were previously additive — now each upgrade fully strips the previous tier first.

Change — Immortal death reset: onRespawn in ImmortalListener now resets the stage to 1 on death (if above 1), clears the near-death state and dash cooldown, re-applies Stage 1 powers, and saves to disk. Stage 0 players are unaffected since they haven't rejuvenated yet.

New — Nether Star obtainment: Right-clicking a Nether Star grants The Immortal at Stage 0, consuming one star. Blocked if the player already has any class. Plays a blindness + totem particle + wither sound sequence before granting powers.