fix(ui): complete retail inventory scroll polish

Preserve pixel scroll offsets across inventory rebuilds, crop partially visible rows with nested geometry/UV clips, and replace the obsolete 560px resize ceiling with available screen height. Keep retail's row-sized wheel step while allowing continuous scrollbar thumb positions.

Co-Authored-By: Codex <codex@openai.com>

src/AcDream.App/UI/Layout/InventoryController.cs

@@ -251,6 +251,12 @@ public sealed class InventoryController : IItemListDragHandler, IRetainedPanelCo
 
     public void Populate()
     {
+        // Retail refreshes listbox contents without resetting m_iScrollableY.
+        // Defer our procedural rebuild so the first re-added cell cannot collapse
+        // MaxScroll temporarily and clamp the user's offset back to zero.
+        using IDisposable? contentsLayout = _contentsGrid?.DeferLayout();
+        using IDisposable? containersLayout = _containerList?.DeferLayout();
+
         uint p = _playerGuid();
         uint open = EffectiveOpen();