fix(ui): restore retail magic shortcut bar

Port the retail horizontal ItemList empty-slot padding and share UIItem shortcut-number graphics with the status toolbar. Preserve all authored face children on compound DAT buttons so the three-piece Cast control reflows and renders as one complete button.

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

src/AcDream.App/UI/UiShortcutSlotGraphics.cs

@@ -0,0 +1,12 @@
+namespace AcDream.App.UI;
+
+/// <summary>
+/// Shared DAT presentation assets for UIItem shortcut cells. Both gmToolbarUI and
+/// gmSpellcastingUI use UIElement_UIItem::SetShortcutNum @ 0x004E1590, so their
+/// digit arrays and empty-cell prototype must come from one resolved asset set.
+/// </summary>
+public sealed record UiShortcutSlotGraphics(
+    uint[]? RegularDigits,
+    uint[]? GhostedDigits,
+    uint[]? EmptyDigits,
+    uint EmptySprite);