feat(D.5.1): thread CreateObject IconId into ItemRepository via spawn event

Added uint IconId = 0 (defaulted, last positional param) to the EntitySpawn
record so existing call sites outside WorldSession compile unchanged. The
WorldSession invoke now passes parsed.Value.IconId as the final arg.
OnLiveEntitySpawned calls Items.EnrichItem unconditionally — it's a no-op
for non-item spawns (players/NPCs/furniture aren't in the repo), so the call
is safe for every incoming CreateObject.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/AcDream.App/Rendering/GameWindow.cs

@@ -2495,6 +2495,10 @@ public sealed class GameWindow : IDisposable
     /// </summary>
     private void OnLiveEntitySpawned(AcDream.Core.Net.WorldSession.EntitySpawn spawn)
     {
+        // D.5.1: enrich a known inventory/equipped item (stubbed from PlayerDescription)
+        // with the icon/name/type its CreateObject carries, so the toolbar can render it.
+        Items.EnrichItem(spawn.Guid, spawn.IconId, spawn.Name ?? string.Empty, (AcDream.Core.Items.ItemType)(spawn.ItemType ?? 0));
+
         // Phase A.1 hotfix: live CreateObject handler reads dats extensively
         // (Setup, GfxObj, Surface, SurfaceTexture) to hydrate the spawned
         // entity. All of it must run under the dat lock so it doesn't race