feat(D.2b): vitals numbers as UiText (widget-generalization Task 8)

The vitals cur/max numbers now render through the generic UiText widget — retail
gmVitalsUI uses UIElement_Text for them, not a meter-internal label. VitalsController
attaches a centered, non-interactive UiText child to each meter and stops the meter
drawing its own label (UiMeter.Label -> null). New UiText.Centered draws the first line
centered H+V with the SAME formula UiMeter's overlay used, so the numbers are
pixel-identical — user-confirmed in the live client.

This completes the D.2b widget-generalization pass: every chat + vitals widget is now
built generically and registered to its retail Type (Button/Field*/Menu/Meter/Scrollbar/
Text), with thin find-by-id controllers. (*Field is controller-placed; Type 3 stays
UiDatElement for chrome.)

Divergence register: AP-37 vitals-numbers-via-UiMeter.Label clause retired. Full suite:
404 passed, 2 skipped, 0 failed.

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

src/AcDream.App/UI/Layout/VitalsController.cs

@@ -1,4 +1,6 @@
 using System;
+using System.Numerics;
+using AcDream.App.UI;
 
 namespace AcDream.App.UI.Layout;
 
@@ -53,16 +55,44 @@ public static class VitalsController
         BindMeter(layout, Mana,    manaPct,    manaText);
     }
 
+    /// <summary>White cur/max numbers — matches the former <c>UiMeter.LabelColor</c> default.</summary>
+    private static readonly Vector4 NumberColor = new(1f, 1f, 1f, 1f);
+
     private static void BindMeter(
         ImportedLayout layout, uint id,
         Func<float>  pct,
         Func<string> text)
     {
-        if (layout.FindElement(id) is UiMeter m)
+        // Silently skip if the id is absent — missing meters are not an error (partial layouts).
+        if (layout.FindElement(id) is not UiMeter m) return;
+
+        m.Fill = () => pct();
+
+        // Retail gmVitalsUI renders the cur/max as a real UIElement_Text centered over the
+        // bar — NOT a meter-internal label. Attach a centered UiText (non-interactive
+        // decoration) that fills + stretches with the meter, and stop the meter drawing its
+        // own label. UiText.Centered uses the SAME centering formula the meter's overlay did,
+        // so the numbers stay pixel-identical (locked by the visual gate).
+        m.Label = () => null;
+
+        var number = new UiText
         {
-            m.Fill  = () => pct();
-            m.Label = () => text();
-        }
-        // Silently skip if the id is absent — missing meters are not an error.
+            Left = 0f, Top = 0f, Width = m.Width, Height = m.Height,
+            Anchors = AnchorEdges.Left | AnchorEdges.Top | AnchorEdges.Right | AnchorEdges.Bottom,
+            Centered = true,
+            DatFont  = m.DatFont,        // the same dat font the meter used for its label
+            ClickThrough = true,         // decoration: no focus / selection / drag
+            AcceptsFocus = false,
+            IsEditControl = false,
+            CapturesPointerDrag = false,
+            LinesProvider = () =>
+            {
+                var s = text();
+                return string.IsNullOrEmpty(s)
+                    ? Array.Empty<UiText.Line>()
+                    : new[] { new UiText.Line(s, NumberColor) };
+            },
+        };
+        m.AddChild(number);
     }
 }

src/AcDream.App/UI/UiText.cs

@@ -63,6 +63,14 @@ public sealed class UiText : UiElement
     /// <summary>Inner text inset from the view edges, px.</summary>
     public float Padding { get; set; } = 4f;
 
+    /// <summary>Static centered single-line mode (retail <c>UIElement_Text</c> center
+    /// justification): draws the FIRST line centered horizontally AND vertically in the
+    /// element rect, with NO scroll/selection machinery. Used for static labels such as
+    /// the vitals cur/max numbers. The centering formula is IDENTICAL to
+    /// <see cref="UiMeter"/>'s former number overlay so those numbers stay pixel-identical
+    /// after the rewire. Pair with <c>ClickThrough = true</c> for non-interactive labels.</summary>
+    public bool Centered { get; set; }
+
     /// <summary>The scroll model — also read by the linked UiScrollbar.</summary>
     public UiScrollable Scroll { get; } = new();
 
@@ -122,6 +130,29 @@ public sealed class UiText : UiElement
         // submitted first → text on top.
         ctx.DrawFill(0, 0, Width, Height, BackgroundColor);
 
+        // Static centered single-line mode (vitals cur/max numbers etc.): draw the first
+        // line centered H+V with the SAME formula UIElement_Meter used for its label, then
+        // skip the scroll/selection machinery entirely.
+        if (Centered)
+        {
+            var cLines = LinesProvider();
+            if (cLines.Count == 0) return;
+            var line0 = cLines[0];
+            if (DatFont is { } cdf)
+            {
+                float cx = (Width - cdf.MeasureWidth(line0.Text)) * 0.5f;
+                float cy = (Height - cdf.LineHeight) * 0.5f;
+                ctx.DrawStringDat(cdf, line0.Text, cx, cy, line0.Color);
+            }
+            else if ((Font ?? ctx.DefaultFont) is { } cbf)
+            {
+                float cx = (Width - cbf.MeasureWidth(line0.Text)) * 0.5f;
+                float cy = (Height - cbf.LineHeight) * 0.5f;
+                ctx.DrawString(line0.Text, cx, cy, line0.Color, cbf);
+            }
+            return;
+        }
+
         // Prefer the retail dat font when set; fall back to BitmapFont.
         var datFont = DatFont;
         var bitmapFont = datFont is null ? (Font ?? ctx.DefaultFont) : null;