checkpoint(render): portal-haze root cause — emitters need own-cell membership (S2 chunk 6 contract)

Instrumented arrivals show the Hidden-state cloud's emitters spawn in the
arrival cell, become view-eligible when the world appears, and are never
drawn: the walk draws an owner's emitters only through the owner's registry
rows, and a hidden owner's shadow is suspended. Retail's
CPhysicsObj::add_particle_shadow_to_cell (0x00514a70) gives an emitter one
shadow in its own cell, drawn at that cell's turn regardless of the parent's
hidden state. S2 chunk 6 (packet §10) ports that: per-cell emitter draw
membership, owner-union particle path deleted. Route timing fixed so the
arrival screenshots anchor on the reveal.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/AcDream.App/World/LiveEntityPresentationController.cs

@@ -21,6 +21,9 @@ public sealed class LiveEntityPresentationController : IDisposable
     public const uint UnHideScriptType = 0x75u;
     public const uint HiddenScriptType = 0x76u;
 
+    private static readonly bool HiddenTraceEnabled =
+        Environment.GetEnvironmentVariable("ACDREAM_DUMP_PLAYSCRIPT") == "1";
+
     private readonly LiveEntityRuntime _liveEntities;
     private readonly ShadowObjectRegistry _shadows;
     private readonly Func<uint, uint, float, bool> _playTyped;