feat(ui): inventory/shortcut/paperdoll item-name tooltips — UIElement_UIItem::UpdateTooltip port

Retail UIElement_UIItem::UpdateTooltip @0x004E1CB0 caches the item's
NAME_APPROPRIATE display name (stack-count-prefixed "%d %s" when
StackSize > 1) as m_TTText every UIItem_Update refresh; the generic
UIElementManager::CheckTooltip dwell timer is what actually shows it
on hover — no special-cased trigger of its own.

UiItemSlot cells are built programmatically (never through
LayoutImporter.Build), so #409's original round left this deferred:
the class carried neither the popup locator (P0x47/P0x48) nor a name
source. A live-DAT sweep of the shared UIItem cell-template catalog
(ItemListCellTemplate.CatalogLayoutId, 0x21000037) found all 47
UIItem-type (class 0x10000032) prototypes — inventory's cell, every
toolbar slot, every paperdoll/armor slot skin — resolve the IDENTICAL
popup locator (P0x47=0x10000395/P0x48=0x21000041) through catalog
inheritance, with no literal text authored on any of them. UiItemSlot
now hardcodes that pair and exposes GetTooltipText() via a new
TooltipTextResolve delegate, wired at every physical-item
construction site: InventoryController (main-pack cell + grid cells),
ExternalContainerController, PaperdollController (closes the
separate gmPaperDollUI::UpdateItemSlotTooltip @0x004A52EF gap too —
same cell class, same fix), VendorUiController (shop/buying/selling
lists), SecureTradeUiController, ToolbarController.

Text is the new ClientObject.GetTooltipDisplayName(): GetAppropriateName()
prefixed with the stack count via "{count} {name}" when StackSize > 1,
matching UpdateTooltip's exact NAME_APPROPRIATE + "%d %s" sprintf.
UiCatalogSlot (spell/component catalog cells, a different UiItemSlot
subclass) is unaffected — it already overrides GetTooltipText() with
its own Label.

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

src/AcDream.App/UI/UiItemSlot.cs

@@ -12,13 +12,63 @@ namespace AcDream.App.UI;
 /// </summary>
 public class UiItemSlot : UiElement
 {
-    public UiItemSlot() { ClickThrough = false; }
+    /// <summary>
+    /// Retail's shared UIItem cell-template catalog (<c>ItemListCellTemplate.
+    /// CatalogLayoutId</c>, LayoutDesc <c>0x21000037</c>) authors the SAME
+    /// tooltip popup locator on every one of its 49 standalone prototypes —
+    /// live-DAT-probed 2026-08-16: every top-level catalog child (inventory's
+    /// 32x32 cell <c>0x1000033A</c>, the toolbar's per-slot prototypes
+    /// <c>0x1000043B</c>.., the container cell <c>0x1000033F</c>, and every
+    /// paperdoll/armor slot skin alike) resolves <c>P0x47=0x10000395</c> /
+    /// <c>P0x48=0x21000041</c> through catalog inheritance, matching one of
+    /// the four popup skins <see cref="Layout.RetailTooltipPresenter"/> already
+    /// mounts for every other tooltip-bearing element
+    /// (<c>Layout.TooltipLiveDatTests.PopupSkinRootIds</c>). Since
+    /// <see cref="UiItemSlot"/> cells are built programmatically (never through
+    /// <c>LayoutImporter.Build</c>), this port hardcodes the uniform pair here
+    /// rather than re-deriving it per instance — the same "exhaustive scan,
+    /// then hardcode" shape as <c>RetailCursorCatalog</c>'s five window-control
+    /// cursor DIDs and <c>ItemListCellTemplate.CatalogLayoutId</c> itself.
+    /// </summary>
+    private const uint ItemTooltipRootElementId = 0x10000395u;
+    private const uint ItemTooltipLayoutDid = 0x21000041u;
+
+    public UiItemSlot()
+    {
+        ClickThrough = false;
+        AuthoredTooltipRootElementId = ItemTooltipRootElementId;
+        AuthoredTooltipLayoutDid = ItemTooltipLayoutDid;
+    }
 
     public override bool ConsumesDatChildren => true;
 
     /// <summary>Bound weenie guid (0 = empty). Retail UIElement_UIItem::itemID.</summary>
     public uint ItemId { get; private set; }
 
+    /// <summary>
+    /// Resolves <see cref="ItemId"/> to its retail tooltip text (a
+    /// <see cref="AcDream.Core.Items.ClientObject.GetTooltipDisplayName"/>
+    /// call bound by the owning controller — every construction site already
+    /// has a <c>ClientObjectTable</c> reference in scope, matching how
+    /// <see cref="SpriteResolve"/> is wired). Null/empty result shows no
+    /// tooltip, matching retail's <c>UIItem_Update</c> early-out
+    /// (<c>weenObj == 0</c> -&gt; <c>UIElement::ClearTooltip</c>) for an
+    /// empty or not-yet-materialized cell.
+    /// </summary>
+    public Func<uint, string?>? TooltipTextResolve { get; set; }
+
+    /// <summary>
+    /// Port of <c>UIElement_UIItem::UpdateTooltip @0x004E1CB0</c>: called every
+    /// refresh (retail's own callers are heartbeat/state-change driven), but
+    /// computed lazily here — the same "runtime text on demand" shape already
+    /// established by <see cref="UiButton.GetTooltipText"/> and
+    /// <see cref="UiRadar.GetTooltipText"/> — rather than cached at
+    /// <see cref="SetItem"/> time, since nothing observes a stale value between
+    /// item-state changes and the next hover dwell.
+    /// </summary>
+    public override string? GetTooltipText()
+        => ItemId != 0 ? TooltipTextResolve?.Invoke(ItemId) : null;
+
     /// <summary>Pre-composited icon GL texture for the bound item (0 = none).</summary>
     public uint IconTexture { get; private set; }