fix: trade gate round 4 - "The trade has been cancelled." + retail's

staged-item trading marker

- Cancel text: ClientTradeSystem::Handle_Trade__Recv_CloseTrade
  @0x0056DE30 shows "The trade has been cancelled." UNCONDITIONALLY
  (every close reason) as 0x1A ClientLocal - the yellow top-center
  SpewBox line. Wired at the router's onTradeClose beside ApplyClose;
  the string lives in ClientTextRefusals with its citation.
- Staged-item marker: retail's mechanism decoded end-to-end - the
  UIItem prototype (catalog 0x21000037) authors overlay child
  0x10000438 (sprite 0x06001DAE, the green frame + corner trade icon),
  bound @0x004E18FC and SetVisible(tradeState != 0) @0x004E2420;
  gmSecureTradeUI::AddItem @0x004CA801 sets
  ACCWeenieObject::SetTradeState(1) on YOUR staged items. Ported as:
  UiItemSlot.ShowTradeOverlay + TradeOverlaySprite (drawn over the
  icon), set on the trade window's self-grid cells; and
  RuntimeTradeState now borrows the canonical object table and
  maintains ClientObject.TradeState (1 at stage, 0 at remove/failure/
  reset/close/clear) - which also brings the ALREADY-PORTED placement
  policy's "You cannot move an item while it is being traded" refusal
  to life (its input field previously had no live producer).

Runtime 1,626, App 4,992/3 - green.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/AcDream.Runtime/Gameplay/RuntimeTradeState.cs

@@ -60,6 +60,7 @@ public interface IRuntimeTradeView
 public sealed class RuntimeTradeState : IDisposable
 {
     private readonly object _gate = new();
+    private readonly AcDream.Core.Items.ClientObjectTable? _objects;
     private readonly List<uint> _selfItems = [];
     private readonly List<uint> _partnerItems = [];
     private bool _isOpen;
@@ -71,7 +72,17 @@ public sealed class RuntimeTradeState : IDisposable
     private long _revision;
     private bool _disposed;
 
-    public RuntimeTradeState() => View = new TradeView(this);
+    /// <summary>Borrows the canonical object table (optional for bare
+    /// fixtures) so YOUR staged items carry retail's client-side trade
+    /// state — <c>ACCWeenieObject::SetTradeState(1) @ 0x004CA801</c> at
+    /// stage, cleared on remove/failure/reset/close. The existing placement
+    /// policy's "You cannot move an item while it is being traded" reads
+    /// this exact field.</summary>
+    public RuntimeTradeState(AcDream.Core.Items.ClientObjectTable? objects = null)
+    {
+        _objects = objects;
+        View = new TradeView(this);
+    }
 
     public IRuntimeTradeView View { get; }
 
@@ -133,6 +144,8 @@ public sealed class RuntimeTradeState : IDisposable
                 : _selfItems;
             if (!items.Contains(update.ItemGuid))
                 items.Add(update.ItemGuid);
+            if (update.Side != (uint)RuntimeTradeSide.Partner)
+                SetTradeState(update.ItemGuid, 1);
             // Staging changes invalidate prior acceptance server-side (ACE
             // re-arms via ClearTradeAcceptance; mirrored defensively here so
             // a dropped 0x0208 cannot leave a stale green check).
@@ -153,7 +166,11 @@ public sealed class RuntimeTradeState : IDisposable
             if (!_isOpen) return;
             bool removed = _selfItems.Remove(update.ItemGuid);
             removed |= _partnerItems.Remove(update.ItemGuid);
-            if (removed) Bump();
+            if (removed)
+            {
+                SetTradeState(update.ItemGuid, 0);
+                Bump();
+            }
         }
     }
 
@@ -193,6 +210,7 @@ public sealed class RuntimeTradeState : IDisposable
         {
             ObjectDisposedException.ThrowIf(_disposed, this);
             if (!_isOpen) return;
+            ClearSelfTradeStates();
             _selfItems.Clear();
             _partnerItems.Clear();
             _selfAccepted = false;
@@ -212,6 +230,7 @@ public sealed class RuntimeTradeState : IDisposable
             if (!_isOpen) return;
             _selfItems.Remove(failure.ItemGuid);
             _partnerItems.Remove(failure.ItemGuid);
+            SetTradeState(failure.ItemGuid, 0);
             _lastFailureItemGuid = failure.ItemGuid;
             _lastFailureReason = failure.Reason;
             Bump();
@@ -260,6 +279,21 @@ public sealed class RuntimeTradeState : IDisposable
         }
     }
 
+    /// <summary>Retail clears the client-side trade state on every staged
+    /// item at reset/close (<c>Trade::Reset</c> tail — the same lifecycle
+    /// gmSalvageUI::ClearAllTradeStates mirrors for its lists).</summary>
+    private void ClearSelfTradeStates()
+    {
+        foreach (uint guid in _selfItems)
+            SetTradeState(guid, 0);
+    }
+
+    private void SetTradeState(uint itemGuid, int state)
+    {
+        if (_objects?.Get(itemGuid) is { } item)
+            item.TradeState = state;
+    }
+
     private void ClearLocked()
     {
         bool changed = _isOpen
@@ -267,6 +301,7 @@ public sealed class RuntimeTradeState : IDisposable
             || _partnerItems.Count != 0
             || _selfAccepted
             || _partnerAccepted;
+        ClearSelfTradeStates();
         _isOpen = false;
         _partnerGuid = 0u;
         _selfItems.Clear();