feat(necro): implement Milestone M3 Necromancer Curses Tree (10 skills)
- Implement core curse formulas (radius, duration, debuff stats, immunity breaking)
- Enforce 1.13c ground truth invariants:
* Amplify Damage (-100% phys res, or -20% on immune)
* Decrepify (-50% phys res / -10% on immune, -50% speed, -50% attack rate, -50% damage dealt)
* Lower Resist (-dm56% on fire/lightning/cold/poison, 1/5th penalty on immune)
* Life Tap (50% physical life leech on hit)
* Iron Maiden (reflects 200%..675% physical melee damage back to attacker)
* Weaken (-33% damage dealt)
* Attract (cursetype = 2, immune to overwrite, cannot recast on attracted unit)
* Mental curse immunity for Bosses & Champions (Dim Vision, Terror, Confuse, Attract)
* 2:1 isometric radius targeting and overhead animated overlays
- Add primary verification suite (tests/skills/nec/curses.test.ts)
- Add adversarial challenger stress suite (tests/skills/nec/adv-curses-stress.test.ts)
troytt
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