fix(items): complete retail corpse looting feedback

Route corpse Use through the shared ItemHolder policy so Stuck corpses open instead of being sent as pickup requests. Restore the framed, horizontally resizable external-container strip and use a compact initial width. Port retail's target-list pending item projection so loot is marked in the chosen inventory slot without changing canonical ownership before the server confirms.

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

tests/AcDream.App.Tests/UI/Layout/ExternalContainerControllerTests.cs

@@ -14,6 +14,40 @@ public sealed class ExternalContainerControllerTests
 
     private sealed class TestElement : UiElement { }
 
+    [Fact]
+    public void WindowPolicy_AddsOuterFrameAndAllowsHorizontalResize()
+    {
+        var screen = new UiRoot { Width = 1280f, Height = 720f };
+        var root = new TestElement
+        {
+            Left = 0f,
+            Top = 400f,
+            Width = 800f,
+            Height = 110f,
+        };
+        RetailWindowFrame.Options options =
+            ExternalContainerController.CreateWindowOptions(root);
+
+        RetailWindowHandle handle = RetailWindowFrame.Mount(
+            screen,
+            root,
+            static _ => (0u, 0, 0),
+            options);
+
+        var frame = Assert.IsType<UiNineSlicePanel>(handle.OuterFrame);
+        Assert.Equal(710f, frame.Width);
+        Assert.Equal(120f, frame.Height);
+        Assert.Equal(170f, frame.MinWidth);
+        Assert.True(frame.Draggable);
+        Assert.True(frame.Resizable);
+        Assert.True(frame.ResizeX);
+        Assert.False(frame.ResizeY);
+        Assert.Equal(ResizeEdges.Left | ResizeEdges.Right, frame.ResizableEdges);
+        Assert.True(frame.ConstrainResizeToParent);
+        Assert.False(frame.DrawCenterFill);
+        Assert.Equal(700f, root.Width);
+    }
+
     private sealed class Harness : IDisposable
     {
         public readonly ExternalContainerState State = new();