feat: port retail magic lifecycle and retained spell UI

Complete the retail cast-intent, target, component, enchantment, and busy-state paths; mount the DAT-authored spell bar, spellbook, component book, effects panels, and shared panel lifecycle; and add scoped input plus conformance coverage.

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

src/AcDream.App/UI/UiCatalogSlot.cs

@@ -0,0 +1,97 @@
+using System;
+using System.Numerics;
+
+namespace AcDream.App.UI;
+
+/// <summary>
+/// Icon-list cell for non-weenie catalog entries such as spells and components.
+/// It reuses the retail UIItemList geometry without pretending a spell id is an
+/// object GUID and without participating in item drag/drop.
+/// </summary>
+public sealed class UiCatalogSlot : UiItemSlot
+{
+    public uint EntryId { get; set; }
+    public uint CatalogIconTexture { get; set; }
+    /// <summary>Optional second 32x32 layer (retail spell endowment item icon).</summary>
+    public uint CatalogOverlayTexture { get; set; }
+    public string Label { get; set; } = string.Empty;
+    public string? Detail { get; set; }
+    public bool ShowLabel { get; init; }
+
+    public new Action? Clicked { get; set; }
+    public new Action? DoubleClicked { get; set; }
+    public object? CatalogDragPayload { get; init; }
+    public Action<object>? DragBegan { get; init; }
+    public Action<object>? DragEnded { get; init; }
+    public Action<object>? Dropped { get; init; }
+
+    public override string? GetTooltipText() => string.IsNullOrWhiteSpace(Label) ? null : Label;
+
+    public override bool IsDragSource => CatalogDragPayload is not null;
+    public override object? GetDragPayload() => CatalogDragPayload;
+    public override (uint tex, int w, int h)? GetDragGhost() =>
+        CatalogDragPayload is not null && CatalogIconTexture != 0u
+            ? (CatalogIconTexture, 32, 32)
+            : null;
+
+    internal override void SetDragSourceActive(bool active, object? payload)
+    {
+        if (!active && payload is not null) DragEnded?.Invoke(payload);
+    }
+
+    public override bool OnEvent(in UiEvent e)
+    {
+        switch (e.Type)
+        {
+            case UiEventType.MouseDown:
+                return true;
+            case UiEventType.Click:
+                Clicked?.Invoke();
+                return true;
+            case UiEventType.DoubleClick:
+                DoubleClicked?.Invoke();
+                return true;
+            case UiEventType.DragBegin:
+                if (e.Payload is not null) DragBegan?.Invoke(e.Payload);
+                return true;
+            case UiEventType.DragEnter:
+            case UiEventType.DragOver:
+                return true;
+            case UiEventType.DropReleased:
+                if (e.Payload is not null) Dropped?.Invoke(e.Payload);
+                return true;
+            default:
+                return false;
+        }
+    }
+
+    protected override void OnDraw(UiRenderContext ctx)
+    {
+        float iconSize = ShowLabel ? MathF.Min(32f, Height) : Width;
+        if (CatalogIconTexture != 0)
+            ctx.DrawSprite(CatalogIconTexture, 0f, 0f, iconSize, iconSize, 0f, 0f, 1f, 1f, Vector4.One);
+        else if (SpriteResolve is not null && EmptySprite != 0)
+        {
+            var (texture, _, _) = SpriteResolve(EmptySprite);
+            if (texture != 0)
+                ctx.DrawSprite(texture, 0f, 0f, iconSize, iconSize, 0f, 0f, 1f, 1f, Vector4.One);
+        }
+
+        if (CatalogOverlayTexture != 0)
+            ctx.DrawSprite(CatalogOverlayTexture, 0f, 0f, iconSize, iconSize, 0f, 0f, 1f, 1f, Vector4.One);
+
+        if (Selected && SpriteResolve is not null && SelectedSprite != 0)
+        {
+            var (texture, _, _) = SpriteResolve(SelectedSprite);
+            if (texture != 0)
+                ctx.DrawSprite(texture, 0f, 0f, Width, Height, 0f, 0f, 1f, 1f, Vector4.One);
+        }
+
+        if (ShowLabel)
+        {
+            ctx.DrawString(Label, iconSize + 4f, 3f, new Vector4(0.92f, 0.88f, 0.70f, 1f));
+            if (!string.IsNullOrWhiteSpace(Detail))
+                ctx.DrawString(Detail!, MathF.Max(iconSize + 4f, Width - 48f), 3f, Vector4.One);
+        }
+    }
+}