feat(D.2b): VitalsController — bind live vitals data by element id

Mirrors retail gmVitalsUI::PostInit: grab Health/Stamina/Mana meters from
the imported layout by their dat element ids (0x100000E6 / EC / EE) and
wire Func<float> fill + Func<string> label providers. Missing ids are
silently skipped (no throw). Slice sprites + dat font already set by the
factory — this is pure data wiring, not graphics.

3 TDD tests: single-meter fill+label, all-three distinct providers, missing-id no-throw.

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

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

@@ -0,0 +1,102 @@
+using AcDream.App.UI;
+using AcDream.App.UI.Layout;
+
+namespace AcDream.App.Tests.UI.Layout;
+
+/// <summary>
+/// Unit tests for <see cref="VitalsController.Bind"/>: verifies that the controller
+/// correctly maps element ids to UiMeter instances and wires the Fill / Label providers.
+/// No dats, no GL — pure data-wiring tests.
+/// </summary>
+public class VitalsBindingTests
+{
+    // ── Test 1: Health meter Fill + Label providers are bound ─────────────────
+
+    [Fact]
+    public void Bind_SetsHealthMeterFillFromProvider()
+    {
+        var health = new UiMeter();
+        var layout = FakeLayout(("0x100000E6", health));
+        float hp = 0.42f;
+
+        VitalsController.Bind(layout,
+            healthPct:    () => hp,
+            staminaPct:   () => 1f,
+            manaPct:      () => 1f,
+            healthText:   () => "42/100",
+            staminaText:  () => "",
+            manaText:     () => "");
+
+        Assert.Equal(0.42f, health.Fill()!.Value);
+        Assert.Equal("42/100", health.Label());
+    }
+
+    // ── Test 2: All three meters wired to distinct providers ──────────────────
+
+    [Fact]
+    public void Bind_AllThreeMeters_EachBoundToOwnProvider()
+    {
+        var health  = new UiMeter();
+        var stamina = new UiMeter();
+        var mana    = new UiMeter();
+        var layout  = FakeLayout(
+            ("0x100000E6", health),
+            ("0x100000EC", stamina),
+            ("0x100000EE", mana));
+
+        VitalsController.Bind(layout,
+            healthPct:   () => 0.25f,
+            staminaPct:  () => 0.50f,
+            manaPct:     () => 0.75f,
+            healthText:  () => "25/100",
+            staminaText: () => "50/100",
+            manaText:    () => "75/100");
+
+        // Each meter should reflect its own provider, not another's.
+        Assert.Equal(0.25f, health.Fill()!.Value);
+        Assert.Equal("25/100", health.Label());
+
+        Assert.Equal(0.50f, stamina.Fill()!.Value);
+        Assert.Equal("50/100", stamina.Label());
+
+        Assert.Equal(0.75f, mana.Fill()!.Value);
+        Assert.Equal("75/100", mana.Label());
+    }
+
+    // ── Test 3: Missing meter ids are silently skipped (no throw) ─────────────
+
+    [Fact]
+    public void Bind_MissingMeterIds_DoesNotThrow()
+    {
+        // Only Health is present; Stamina and Mana are absent from the layout.
+        var health = new UiMeter();
+        var layout = FakeLayout(("0x100000E6", health));
+
+        // Should not throw even though Stamina/Mana are missing.
+        VitalsController.Bind(layout,
+            healthPct:   () => 1f,
+            staminaPct:  () => 1f,
+            manaPct:     () => 1f,
+            healthText:  () => "100/100",
+            staminaText: () => "100/100",
+            manaText:    () => "100/100");
+
+        // Health was present — it should be wired.
+        Assert.Equal(1f, health.Fill()!.Value);
+    }
+
+    // ── Helpers ───────────────────────────────────────────────────────────────
+
+    private static ImportedLayout FakeLayout(params (string idHex, UiElement e)[] items)
+    {
+        var dict = new Dictionary<uint, UiElement>();
+        var root = new UiPanel();
+        foreach (var (idHex, e) in items)
+        {
+            uint id = Convert.ToUInt32(idHex, 16);
+            root.AddChild(e);
+            dict[id] = e;
+        }
+        return new ImportedLayout(root, dict);
+    }
+}