fix(vfx #C.1.5a): seed entity rotation in activator so hook offset rotates

Visual verification at the Holtburg Town network portal revealed the swirl
was oriented along world axes (NS) instead of the portal's actual facing
(EW), and partially buried in the ground because the hook's local-frame
Offset.Origin was being applied in world axes too.

Root cause: EntityScriptActivator.OnCreate fired _scriptRunner.Play but
never called _particleSink.SetEntityRotation. When the runner's
CreateParticleHook fires, the sink reads per-entity rotation from
_rotationByEntity (defaults to Quaternion.Identity for unknown entities)
and uses it to transform the hook's Offset.Origin from entity-local to
world space. Without the seed call, the rotation lookup falls through to
Identity and the offset goes off along world XYZ.

Fix is a single SetEntityRotation call before the Play call. Added a 4th
unit test that constructs an entity with a 90 deg yaw and asserts the spawned
particle's world position reflects the rotated offset.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/AcDream.App/Rendering/Vfx/EntityScriptActivator.cs

@@ -68,6 +68,14 @@ public sealed class EntityScriptActivator
         uint scriptId = _defaultScriptResolver(entity);
         if (scriptId == 0) return;
 
+        // Seed the sink's per-entity rotation so CreateParticleHook.Offset.Origin
+        // (in entity-local frame) transforms correctly to world space when the
+        // hook fires. Without this, the sink falls through to Quaternion.Identity
+        // and the offset gets applied in world axes — visual symptom for portals:
+        // swirl oriented along world XYZ instead of the portal's facing, partially
+        // buried because the local-Z lift becomes a world-axis offset.
+        _particleSink.SetEntityRotation(entity.ServerGuid, entity.Rotation);
+
         _scriptRunner.Play(scriptId, entity.ServerGuid, entity.Position);
     }