feat(D.2b): controls.ini stylesheet loader + apply title color

Adds ControlsIni — a minimal flat-INI reader for retail's controls.ini
(#AARRGGBB alpha-first color tokens; case-insensitive section/key lookup;
missing file returns an empty sheet with no throw). Wires the [title]
color token into the vitals panel's UiLabel in GameWindow.OnLoad, with
hardcoded white as the fallback. Visually a no-op (retail's [title] color
is white), but proves the stylesheet plumbing end-to-end (D.2b §7).
Three unit tests cover section parsing, #AARRGGBB decode, and graceful
missing-file handling.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/AcDream.App.Tests/UI/ControlsIniTests.cs

@@ -0,0 +1,38 @@
+using System.Numerics;
+using AcDream.App.UI;
+
+namespace AcDream.App.Tests.UI;
+
+public class ControlsIniTests
+{
+    [Fact]
+    public void Parse_ReadsSectionTokens()
+    {
+        var ini = ControlsIni.Parse(
+            "[title]\nheight=19\ncolor=#FFFFFFFF\nfont=font://Verdana-10-bold\n" +
+            "[body]\nbgcolor=#00000000\ncolor_border=#FF4F657D\n");
+
+        Assert.Equal("19", ini.Get("title", "height"));
+        Assert.Equal("font://Verdana-10-bold", ini.Get("title", "font"));
+        Assert.Null(ini.Get("title", "missing"));
+        Assert.Null(ini.Get("nosuch", "height"));
+    }
+
+    [Fact]
+    public void TryColor_ParsesAlphaFirstHex()
+    {
+        var ini = ControlsIni.Parse("[body]\ncolor_border=#FF4F657D\n");
+        Assert.True(ini.TryColor("body", "color_border", out Vector4 c));
+        Assert.Equal(0xFF / 255f, c.W, 5); // alpha
+        Assert.Equal(0x4F / 255f, c.X, 5); // red
+        Assert.Equal(0x65 / 255f, c.Y, 5); // green
+        Assert.Equal(0x7D / 255f, c.Z, 5); // blue
+    }
+
+    [Fact]
+    public void Load_MissingFileReturnsEmptyNotThrow()
+    {
+        var ini = ControlsIni.Load(@"Z:\does\not\exist\controls.ini");
+        Assert.Null(ini.Get("title", "height")); // empty, no throw
+    }
+}