fix(client): restore retail interaction parity

Harden keyboard and camera routing, inventory and vendor interactions, chat/emotes, relog portal flow, and paperdoll rendering. Add retail research, connected gate coverage, and release-gate validation.

tests/AcDream.App.Tests/UI/DragDropSpineTests.cs

@@ -182,6 +182,38 @@ public class DragDropSpineTests
         Assert.Equal((0x99u, 32, 32), root.DragGhostForTest);
     }
 
+    [Fact]
+    public void RootOwnedDrag_survivesProceduralSourceCellReplacement_untilRelease()
+    {
+        var (root, list, cell) = RootWithBoundSlot(0x5001u);
+        object? released = null;
+        root.DragReleasedOutsideUi += (payload, _, _) => released = payload;
+
+        root.OnMouseDown(UiMouseButton.Left, 10, 10);
+        root.OnMouseMove(20, 10);                            // BeginDrag → root owns ghost
+        object payload = Assert.IsType<ItemDragPayload>(root.DragPayload);
+
+        // InventoryController.Populate/ExternalContainerController.Populate use
+        // UiItemList.Flush when an unrelated authoritative item update arrives.
+        // The old source cell is replaced while the physical button is still down.
+        list.Flush();
+
+        Assert.Null(cell.Parent);
+        Assert.Same(cell, root.DragSource);
+        Assert.Same(payload, root.DragPayload);
+        Assert.Equal((0x99u, 32, 32), root.DragGhostForTest);
+        Assert.Same(root, root.Captured);                    // retail drag element owns capture
+
+        root.OnMouseMove(600, 500);
+        root.OnMouseUp(UiMouseButton.Left, 600, 500);
+
+        Assert.Same(payload, released);
+        Assert.Null(root.DragSource);
+        Assert.Null(root.DragPayload);
+        Assert.Null(root.DragGhostForTest);
+        Assert.Null(root.Captured);
+    }
+
     [Fact]
     public void FinishDrag_overNothing_deliversNoDrop_butLiftStands()
     {