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/UI/Layout/RetailPanelUiControllerTests.cs

@@ -0,0 +1,90 @@
+using AcDream.App.UI.Layout;
+
+namespace AcDream.App.Tests.UI.Layout;
+
+public sealed class RetailPanelUiControllerTests
+{
+    [Fact]
+    public void ShowingPanel_HidesCurrent_AndClosingLeavesHostEmpty()
+    {
+        var visible = new Dictionary<string, bool>(StringComparer.Ordinal)
+        {
+            ["inventory"] = false,
+            ["helpful"] = false,
+        };
+        var controller = Create(visible);
+        controller.Register(7u, "inventory");
+        controller.Register(4u, "helpful");
+
+        Assert.True(controller.SetPanelVisibility(7u, true));
+        Assert.True(visible["inventory"]);
+        Assert.Equal(7u, controller.ActivePanelId);
+
+        Assert.True(controller.SetPanelVisibility(4u, true));
+        Assert.False(visible["inventory"]);
+        Assert.True(visible["helpful"]);
+        Assert.Equal(4u, controller.ActivePanelId);
+
+        Assert.False(controller.TogglePanel(4u));
+        Assert.False(visible["helpful"]);
+        Assert.Null(controller.ActivePanelId);
+    }
+
+    [Fact]
+    public void RestorePreviousProperty_ReopensOnlyNonRestoringPreviousPanel()
+    {
+        var visible = new Dictionary<string, bool>(StringComparer.Ordinal)
+        {
+            ["ordinary"] = false,
+            ["transient"] = false,
+        };
+        var controller = Create(visible);
+        controller.Register(1u, "ordinary", restorePrevious: false);
+        controller.Register(2u, "transient", restorePrevious: true);
+
+        controller.SetPanelVisibility(1u, true);
+        controller.SetPanelVisibility(2u, true);
+        Assert.False(visible["ordinary"]);
+        Assert.True(visible["transient"]);
+
+        controller.SetPanelVisibility(2u, false);
+        Assert.True(visible["ordinary"]);
+        Assert.False(visible["transient"]);
+        Assert.Equal(1u, controller.ActivePanelId);
+    }
+
+    [Fact]
+    public void ObservedPersistenceShow_UsesSameExclusiveLifecycle()
+    {
+        var visible = new Dictionary<string, bool>(StringComparer.Ordinal)
+        {
+            ["first"] = false,
+            ["second"] = false,
+        };
+        var controller = Create(visible);
+        controller.Register(1u, "first");
+        controller.Register(2u, "second");
+        controller.SetPanelVisibility(1u, true);
+
+        visible["second"] = true;
+        controller.ObserveWindowVisibility("second", visible: true);
+
+        Assert.False(visible["first"]);
+        Assert.True(visible["second"]);
+        Assert.Equal(2u, controller.ActivePanelId);
+    }
+
+    private static RetailPanelUiController Create(Dictionary<string, bool> visible)
+        => new(
+            name => visible[name],
+            name =>
+            {
+                visible[name] = true;
+                return true;
+            },
+            name =>
+            {
+                visible[name] = false;
+                return true;
+            });
+}