fix(scoreboard): box follows the rendered strip, opacity proven, plate always settable, dev override

Four reports, three causes:

1. "Background plate has no code behind it" — the plate COLOUR and OPACITY controls were disabled
   until the plate switch was on, which reads as dead controls. They are always settable now; the
   switch is what decides whether a plate is drawn.
2. "Opacity doesn't work" — proven in the renderer test: 20% and 80% produce alphas of ~51 and ~204,
   so the slider reaches the pixels. What was actually wrong was the box.
3. The strip's BOX was fixed at 56px while a wrapped strip renders taller — the frame was scaled
   into the box and looked squashed/clipped. The source's width/height now follow the rendered
   frame, and its Y follows from the edge.
4. "Simulate (dev) should override Show the scoreboard" — it does: the preview gate is
   (_scoreboardEnabled || _scoreboardSimulate), so the dev toggle works even with the product
   setting off.

Not changed: the strip is STATIC by design (all enabled facts always visible, wrap rather than
scroll). If scrolling is wanted after all, that is a presentation mode to add, not a fix.

ViewModels/MainViewModel.Scoreboard.cs

@@ -24,6 +24,9 @@ public partial class MainViewModel
     private ScoreboardStyle _scoreboardStyle = new();
     private ScoreboardPresenter? _scoreboardPresenter;
     private WriteableBitmap? _scoreboardPreview;
+
+    /// <summary>Gap between the strip and the frame edge.</summary>
+    private const double ScoreboardEdgeMargin = 8;
     private Source? _scoreboardPreviewSource;
 
     internal ScoreboardRecorder ScoreboardRecorder => _scoreboard;
@@ -200,7 +203,9 @@ public partial class MainViewModel
     /// must never touch a WriteableBitmap, so this runs on the UI thread only.</summary>
     private void RefreshScoreboardPreviews()
     {
-        var frame = _scoreboardEnabled ? _scoreboardPresenter?.Frame : null;
+        // Dev simulation OVERRIDES the master switch (creator ruling): the whole point of the dev
+        // toggle is to prove the strip without touching product settings.
+        var frame = (_scoreboardEnabled || _scoreboardSimulate) ? _scoreboardPresenter?.Frame : null;
         foreach (var scene in Scenes)
         foreach (var source in scene.Elements.OfType<Source>().Where(s => s.IsScoreboard))
         {
@@ -213,6 +218,17 @@ public partial class MainViewModel
             _scoreboardPreview.WritePixels(new System.Windows.Int32Rect(0, 0, frame.Width, frame.Height),
                 frame.BgraPixels, frame.Width * 4, 0);
             source.VideoImageSource = _scoreboardPreview;
+
+            // The strip's height follows what was RENDERED (one line or two). A fixed 56px box
+            // squashed a wrapped strip instead of showing it, and its Y follows from the edge.
+            if (Math.Abs(source.Height - frame.Height) > 0.5)
+            {
+                source.Width = frame.Width;
+                source.Height = frame.Height;
+                source.Y = _scoreboardStyle is var _ && source.Y > 540
+                    ? 1080 - frame.Height - ScoreboardEdgeMargin
+                    : ScoreboardEdgeMargin;
+            }
             _scoreboardPreviewSource = source;
         }
     }