feat(ui): importer carries dat FontColor (0x1B) onto text widgets; character colors from dat where present

LayoutImporter.ReadState now reads Properties 0x1B (ColorBaseProperty, ARGB bytes) and stores the normalized Vector4 in ElementInfo.FontColor (nullable). ElementReader.Merge propagates it with the same non-null-derived-wins rule as FontDid and HJustify. DatWidgetFactory.BuildText seeds UiText.DefaultColor from FontColor when present.

Diagnosis for LayoutDesc 0x2100002E: ALL 12 header and footer text elements carry NO dat color. Every color is runtime set by CharacterStatController. Comments added at each callsite. No hardcoded colors deleted.

Tests added: 3 ElementReader FontColor Merge + 3 DatWidgetFactory DefaultColor. 702 passed, 0 failed. Screenshots: character window, vitals, toolbar all unchanged.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/AcDream.App.Tests/UI/Layout/DatWidgetFactoryTests.cs

@@ -1,3 +1,4 @@
+using System.Numerics;
 using AcDream.App.UI;
 using AcDream.App.UI.Layout;
 namespace AcDream.App.Tests.UI.Layout;
@@ -299,4 +300,55 @@ public class DatWidgetFactoryTests
         t.Centered = false;        // controller override
         Assert.False(t.Centered);  // override wins
     }
+
+    // ── DefaultColor from dat FontColor (importer Fix B) ─────────────────────
+
+    /// <summary>
+    /// When ElementInfo.FontColor is set (dat carried 0x1B ColorBaseProperty),
+    /// DatWidgetFactory.BuildText must copy it onto UiText.DefaultColor.
+    /// </summary>
+    [Fact]
+    public void BuildText_FontColorPresent_SetsDefaultColor()
+    {
+        var gold = new Vector4(1f, 0.82f, 0.36f, 1f);
+        var info = new ElementInfo { Type = 12, Width = 100, Height = 20, FontColor = gold };
+        var t = Assert.IsType<UiText>(DatWidgetFactory.Create(info, NoTex, null));
+        Assert.Equal(gold, t.DefaultColor);
+    }
+
+    /// <summary>
+    /// When ElementInfo.FontColor is null (dat carried no 0x1B), DefaultColor must
+    /// stay at white (Vector4.One) — the backward-compatible default.
+    /// </summary>
+    [Fact]
+    public void BuildText_FontColorAbsent_DefaultColorIsWhite()
+    {
+        var info = new ElementInfo { Type = 12, Width = 100, Height = 20, FontColor = null };
+        var t = Assert.IsType<UiText>(DatWidgetFactory.Create(info, NoTex, null));
+        Assert.Equal(Vector4.One, t.DefaultColor);
+    }
+
+    /// <summary>
+    /// Backward-compat guarantee: a controller that sets LinesProvider with an
+    /// explicit per-line color AFTER build is unaffected by DefaultColor.
+    /// The controller's per-line color is stored in the Line record, not DefaultColor,
+    /// so DefaultColor changing from dat does not touch existing controller bindings.
+    /// </summary>
+    [Fact]
+    public void BuildText_ControllerExplicitLineColor_UnaffectedByDefaultColor()
+    {
+        // Dat sets a parchment color.
+        var parchment = new Vector4(0.92f, 0.90f, 0.82f, 1f);
+        var info = new ElementInfo { Type = 12, Width = 100, Height = 20, FontColor = parchment };
+        var t = Assert.IsType<UiText>(DatWidgetFactory.Create(info, NoTex, null));
+
+        // Controller overrides with an explicit gold color in the Line record.
+        var gold = new Vector4(1f, 0.82f, 0.36f, 1f);
+        t.LinesProvider = () => new[] { new UiText.Line("text", gold) };
+
+        // The line's color is gold (controller wins), NOT the dat parchment.
+        Assert.Equal(gold, t.LinesProvider()[0].Color);
+        // DefaultColor still holds the dat parchment (unmodified by the controller binding).
+        Assert.Equal(parchment, t.DefaultColor);
+    }
 }