feat(vfx #C.1.5a): construct EntityScriptActivator in GameWindow

Wires the activator into the production lifecycle:
- Construct alongside _wbEntitySpawnAdapter using _scriptRunner +
  _particleSink (both built earlier in OnLoad).
- Production resolver lambda hits _dats.Get<Setup>(...) wrapped in
  try/catch returning 0 on miss/throw — matches ParticleRenderer's
  defensive read pattern.
- Pass into GpuWorldState's new optional ctor parameter.

Closes the wiring half of C.1.5a. Visual verification at the Holtburg
Town network portal is the acceptance gate.

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

src/AcDream.App/Rendering/GameWindow.cs

@@ -33,6 +33,7 @@ public sealed class GameWindow : IDisposable
     /// after <c>OnLoad</c> completes (modern path is mandatory as of N.5).</summary>
     private AcDream.App.Rendering.Wb.WbMeshAdapter? _wbMeshAdapter;
     private AcDream.App.Rendering.Wb.EntitySpawnAdapter? _wbEntitySpawnAdapter;
+    private AcDream.App.Rendering.Vfx.EntityScriptActivator? _entityScriptActivator;
     private AcDream.App.Rendering.Wb.WbDrawDispatcher? _wbDrawDispatcher;
     /// <summary>Phase N.5: ARB_bindless_texture + ARB_shader_draw_parameters
     /// support. Required at startup — missing bindless throws
@@ -1612,6 +1613,30 @@ public sealed class GameWindow : IDisposable
             var wbEntitySpawnAdapter = new AcDream.App.Rendering.Wb.EntitySpawnAdapter(
                 _textureCache!, SequencerFactory, _wbMeshAdapter!);
             _wbEntitySpawnAdapter = wbEntitySpawnAdapter;
+
+            // Phase C.1.5a: construct EntityScriptActivator so server-spawned static
+            // entities (portals first) fire Setup.DefaultScript through the
+            // PhysicsScriptRunner on enter-world. _scriptRunner and _particleSink
+            // are initialised earlier in OnLoad (line ~1083); both are non-null
+            // here. The resolver lambda captures _dats and swallows dat-lookup
+            // throws — see C.1.5a spec §6 (error handling) for rationale.
+            var capturedDatsForActivator = _dats;
+            uint ResolveDefaultScript(AcDream.Core.World.WorldEntity e)
+            {
+                try
+                {
+                    var setup = capturedDatsForActivator?.Get<DatReaderWriter.DBObjs.Setup>(e.SourceGfxObjOrSetupId);
+                    return setup?.DefaultScript.DataId ?? 0u;
+                }
+                catch
+                {
+                    return 0u;
+                }
+            }
+            var entityScriptActivator = new AcDream.App.Rendering.Vfx.EntityScriptActivator(
+                _scriptRunner!, _particleSink!, ResolveDefaultScript);
+            _entityScriptActivator = entityScriptActivator;
+
             // Phase Post-A.5 #53 (Task 12): wire EntityClassificationCache.InvalidateLandblock
             // so Tier 1 cache entries get swept on LB demote (Near to Far) and unload.
             // Per spec §5.3 W3b. The callback receives the canonical landblock id
@@ -1619,7 +1644,8 @@ public sealed class GameWindow : IDisposable
             _worldState = new AcDream.App.Streaming.GpuWorldState(
                 wbSpawnAdapter,
                 wbEntitySpawnAdapter,
-                onLandblockUnloaded: _classificationCache.InvalidateLandblock);
+                onLandblockUnloaded: _classificationCache.InvalidateLandblock,
+                entityScriptActivator: entityScriptActivator);
 
             _wbDrawDispatcher = new AcDream.App.Rendering.Wb.WbDrawDispatcher(
                 _gl, _meshShader!, _textureCache!, _wbMeshAdapter!, _wbEntitySpawnAdapter, _bindlessSupport!,