feat(ui): drive toolbar use state from selection

Port the retail selected-object availability predicate into Core and project it through the shared interaction owner. The imported hand now follows canonical selection/object notices, keeps weapon and targeted-tool activation on the existing wield/use cursor paths, and ghosts empty or explicitly unusable selections per the connected UX requirement.

Co-authored-by: Codex <codex@openai.com>

src/AcDream.App/UI/ItemInteractionController.cs

@@ -496,6 +496,23 @@ public sealed class ItemInteractionController : IDisposable
         return true;
     }
 
+    /// <summary>
+    /// Projects retail <c>gmToolbarUI::HandleSelectionChanged @ 0x004BF380</c>
+    /// from the live selected object's public description. This is deliberately
+    /// a read-only query; activation still flows through <see cref="ActivateItem"/>.
+    /// </summary>
+    public bool IsToolbarUseEnabled(uint selectedObjectId)
+    {
+        if (selectedObjectId == 0
+            || _objects.Get(selectedObjectId) is not { } item)
+            return false;
+
+        return ItemInteractionPolicy.IsToolbarUseEnabled(
+            item.Type,
+            item.CombatUse ?? 0,
+            item.Useability ?? ItemUseability.Undef);
+    }
+
     public bool ActivateItem(uint itemGuid)
     {
         if (itemGuid == 0) return false;