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>

tests/AcDream.App.Tests/Spells/SpellCastingControllerTests.cs

@@ -0,0 +1,119 @@
+using AcDream.App.Spells;
+using AcDream.Core.Spells;
+
+namespace AcDream.App.Tests.Spells;
+
+public sealed class SpellCastingControllerTests
+{
+    [Fact]
+    public void Cast_SelfTargeted_SendsLocalPlayerAsTarget()
+    {
+        Spellbook book = MakeBook(flags: 0x8, untargeted: true, targetMask: 0x10);
+        uint target = 0;
+        var controller = MakeController(book, selected: 99, player: 42,
+            sendTargeted: (id, _) => target = id);
+
+        Assert.Equal(CastRequestResult.Sent, controller.Cast(1));
+        Assert.Equal(42u, target);
+    }
+
+    [Fact]
+    public void Cast_TargetedWithoutSelection_DoesNotSend()
+    {
+        Spellbook book = MakeBook(flags: 0, untargeted: false, targetMask: 0x10);
+        int sends = 0;
+        string message = "";
+        var controller = MakeController(book, selected: null, player: 42,
+            sendTargeted: (_, _) => sends++, display: value => message = value);
+
+        Assert.Equal(CastRequestResult.NoTarget, controller.Cast(1));
+        Assert.Equal(0, sends);
+        Assert.Contains("select", message, StringComparison.OrdinalIgnoreCase);
+    }
+
+    [Fact]
+    public void Cast_Untargeted_StopsThenSendsThenIncrementsBusy()
+    {
+        Spellbook book = MakeBook(flags: 0, untargeted: true, targetMask: 0);
+        var order = new List<string>();
+        var controller = MakeController(book, selected: null, player: 42,
+            stop: () => order.Add("stop"),
+            sendUntargeted: _ => order.Add("send"),
+            incrementBusy: () => order.Add("busy"));
+
+        Assert.Equal(CastRequestResult.Sent, controller.Cast(1));
+        Assert.Equal(["stop", "send", "busy"], order);
+    }
+
+    [Fact]
+    public void Cast_MissingComponents_DoesNotIncrementBusyOrSend()
+    {
+        Spellbook book = MakeBook(flags: 0, untargeted: true, targetMask: 0);
+        int sends = 0, busy = 0;
+        var controller = MakeController(book, selected: null, player: 42,
+            sendUntargeted: _ => sends++, hasComponents: _ => false,
+            incrementBusy: () => busy++);
+
+        Assert.Equal(CastRequestResult.MissingComponents, controller.Cast(1));
+        Assert.Equal(0, sends);
+        Assert.Equal(0, busy);
+    }
+
+    [Fact]
+    public void Cast_Disconnected_DoesNotIncrementBusy()
+    {
+        Spellbook book = MakeBook(flags: 0, untargeted: true, targetMask: 0);
+        int busy = 0;
+        var controller = MakeController(book, selected: null, player: 42,
+            incrementBusy: () => busy++, canSend: () => false);
+
+        Assert.Equal(CastRequestResult.Unavailable, controller.Cast(1));
+        Assert.Equal(0, busy);
+    }
+
+    [Fact]
+    public void Cast_SendThrows_DoesNotIncrementBusyAndRethrows()
+    {
+        Spellbook book = MakeBook(flags: 0, untargeted: true, targetMask: 0);
+        int increments = 0;
+        var controller = MakeController(book, selected: null, player: 42,
+            sendUntargeted: _ => throw new InvalidOperationException("wire"),
+            incrementBusy: () => increments++);
+
+        Assert.Throws<InvalidOperationException>(() => controller.Cast(1));
+        Assert.Equal(0, increments);
+        Assert.Null(controller.LastRequestedSpellId);
+    }
+
+    private static SpellCastingController MakeController(
+        Spellbook book,
+        uint? selected,
+        uint player,
+        Action? stop = null,
+        Action<uint>? sendUntargeted = null,
+        Action<uint, uint>? sendTargeted = null,
+        Action<string>? display = null,
+        Func<uint, bool>? hasComponents = null,
+        Action? incrementBusy = null,
+        Func<bool>? canSend = null) => new(
+            book,
+            () => selected,
+            () => player,
+            stop ?? (() => { }),
+            sendUntargeted ?? (_ => { }),
+            sendTargeted ?? ((_, _) => { }),
+            display ?? (_ => { }),
+            hasRequiredComponents: hasComponents,
+            incrementBusy: incrementBusy,
+            canSend: canSend);
+
+    private static Spellbook MakeBook(uint flags, bool untargeted, uint targetMask)
+    {
+        const string header = "Spell ID,Name,Flags [Hex],IsUntargetted,TargetMask [Hex]";
+        string row = $"1,Test,0x{flags:X},{untargeted},0x{targetMask:X}";
+        SpellTable table = SpellTable.LoadFromReader(new StringReader($"{header}\n{row}"));
+        var book = new Spellbook(table);
+        book.OnSpellLearned(1);
+        return book;
+    }
+}