feat(skills): implement Blizzard (Skill 59) with 1.13c parity and baked missile assets (Ref #400)
- Add authoritative 64-entry circle lookup table (BLIZZARD_CIRCLE_X, BLIZZARD_CIRCLE_Y) matching D2Game.dll 0x6FD1C960 with 2:1 isometric projection (ISO_GROUND_ASPECT_RATIO = 0.5)
- Pack authentic DCC missile sprites (blizzard1..3, blizzardexplode1..2, blizzard4 alias, blizzardexplode3 alias) from d2data.mpq into public/missiles/ and export metadata in missiles-meta.ts
- Implement 1.13c simulation in skills.ts and missile-engine.ts:
* Controller missile 158 blizzardcenter: 100 ticks lifetime, emits 1 falling shard every 4 ticks (Param3=4), coprime step 13 mod 64, radius 7 subtiles
* Falling shards (blizzard1..4): 9 ticks range, vertical screen altitude descent from 120 px to 0 px
* Impact explosions (blizzardexplode1..3): 6 ticks duration, cold damage, 100 ticks chill, NextDelay = 0
* Authentic 5-band level scaling [15, 30, 45, 55, 65] and +5%/pt synergies
- Integrate Blizzard casting in act-scene.ts: spawn blizzardcenter, handle altitude offset, aliased art fallback, and ice_cast_3 overlay
- Add comprehensive 10-case verification test suite (tests/blizzard-missile-113c.test.ts)
troytt
ddad686654