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/IconComposer.cs

@@ -4,6 +4,7 @@ using System.Numerics;
 using AcDream.App.Rendering;
 using AcDream.Core.Items;
 using AcDream.Core.Textures;
+using AcDream.Core.Spells;
 using DatReaderWriter;
 using DatReaderWriter.DBObjs;
 
@@ -35,6 +36,8 @@ public sealed class IconComposer
     private readonly TextureCache _cache;
     private readonly Dictionary<(uint, uint, uint, uint, uint), uint> _byTuple = new();
     private readonly Dictionary<(uint, uint, uint), ComposedIcon> _dragByTuple = new();
+    private readonly Dictionary<uint, uint> _spellIcons = new();
+    private readonly Dictionary<uint, uint> _componentIcons = new();
 
     private sealed record ComposedIcon(byte[] Rgba, int Width, int Height, uint Texture);
 
@@ -298,4 +301,71 @@ public sealed class IconComposer
         var decoded = SurfaceDecoder.DecodeRenderSurface(rs, palette: null);
         layers.Add((decoded.Rgba8, decoded.Width, decoded.Height));
     }
+
+    /// <summary>
+    /// Retail ClientMagicSystem::CompositeSpellIcon (0x00567550): power-level
+    /// backing, spell art, reversed/normal recolor, then self/fellow overlay.
+    /// </summary>
+    public uint GetSpellIcon(uint spellId)
+    {
+        if (_spellIcons.TryGetValue(spellId, out uint cached)) return cached;
+        DatReaderWriter.DBObjs.SpellTable? table =
+            _dats.Get<DatReaderWriter.DBObjs.SpellTable>(0x0E00000Eu);
+        if (table is null || !table.Spells.TryGetValue(spellId, out var spell)) return 0u;
+
+        uint power = spell.Components.Count == 0
+            ? 0u
+            : RetailSpellFormula.DeterminePowerLevelOfComponent(spell.Components[0]);
+        uint powerBacking = RetailDataIdResolver.Resolve(_dats, power, 0x10000006u);
+        var layers = new List<(byte[] rgba, int w, int h)>();
+        AddLayer(layers, powerBacking);
+        AddLayer(layers, spell.Icon);
+        if (layers.Count == 0) return 0u;
+
+        var composed = Compose(layers);
+        uint tintIndex = (spell.Bitfield & DatReaderWriter.Enums.SpellIndex.Reversed) != 0
+            ? 1u : 2u;
+        uint tintDid = RetailDataIdResolver.Resolve(_dats, tintIndex, 0x10000007u);
+        if (TryDecode(tintDid, out DecodedTexture tint))
+            ReplaceWhiteFromSurface(composed.rgba, composed.w, composed.h,
+                tint.Rgba8, tint.Width, tint.Height);
+
+        uint overlayIndex = (spell.Bitfield & DatReaderWriter.Enums.SpellIndex.FellowshipSpell) != 0
+            ? 4u
+            : (spell.Bitfield & DatReaderWriter.Enums.SpellIndex.SelfTargeted) != 0
+                ? 3u : 0u;
+        if (overlayIndex != 0u)
+        {
+            uint overlayDid = RetailDataIdResolver.Resolve(_dats, overlayIndex, 0x10000007u);
+            if (TryDecode(overlayDid, out DecodedTexture overlay))
+                composed = Compose([
+                    (composed.rgba, composed.w, composed.h),
+                    (overlay.Rgba8, overlay.Width, overlay.Height)]);
+        }
+
+        uint texture = _cache.UploadRgba8(composed.rgba, composed.w, composed.h, nearest: true);
+        _spellIcons[spellId] = texture;
+        return texture;
+    }
+
+    /// <summary>
+    /// Retail ClientMagicSystem::CompositeSpellComponentIcon (0x00567720).
+    /// Components use their raw DAT art with pure white replaced by black.
+    /// </summary>
+    public uint GetSpellComponentIcon(uint iconId)
+    {
+        if (iconId == 0u) return 0u;
+        if (_componentIcons.TryGetValue(iconId, out uint cached)) return cached;
+        if (!TryDecode(iconId, out DecodedTexture icon)) return 0u;
+        byte[] rgba = (byte[])icon.Rgba8.Clone();
+        for (int i = 0; i + 3 < rgba.Length; i += 4)
+        {
+            if (rgba[i] != 255 || rgba[i + 1] != 255 || rgba[i + 2] != 255 || rgba[i + 3] != 255)
+                continue;
+            rgba[i] = rgba[i + 1] = rgba[i + 2] = 0;
+        }
+        uint texture = _cache.UploadRgba8(rgba, icon.Width, icon.Height, nearest: true);
+        _componentIcons[iconId] = texture;
+        return texture;
+    }
 }