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/GameRuntime.cs

@@ -255,8 +255,10 @@ public sealed class GameRuntime
 
             // Secure trade (2026-08-14): third sibling J-owner —
             // session-scoped like fellowship (a disconnect closes the trade
-            // server-side), clears at every generation reset.
-            context.Trade = new RuntimeTradeState();
+            // server-side), clears at every generation reset. Borrows the
+            // canonical object table so staged items carry retail's
+            // client-side trade state (SetTradeState @ 0x004CA801).
+            context.Trade = new RuntimeTradeState(context.EntityObjects!.Objects);
             construction.Own(context.Trade);
             Fault(
                 GameRuntimeConstructionPoint.TradeCreated,