Two-slice phase:
- Slice A: ParticleHookSink applies CreateParticleHook.PartIndex via
SetupPartTransforms.Compute(setup.PlacementFrames). Closes#56.
- Slice B: drop EntityScriptActivator's ServerGuid==0 guard so
dat-hydrated EnvCell statics + exterior stabs fire DefaultScript.
Key reality discovery folded into the spec §3: EnvCell.StaticObjects
are already WorldEntities (via GameWindow.BuildInteriorEntitiesForStreaming),
so no synthetic-ID scheme + no new walker class needed — the handoff's
§4 Q1/Q2 options are mooted by entity.Id being collision-free.
Doc-drift fixes from C.1.5a folded into §8.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>