design: the on-stream graphics join the standard (OutputPalette)

The broadcast picture is part of the app, so it stops carrying its own colours. Alert cards, the
ticker and the branding flash now paint from OutputPalette, which Mirrors DESIGN.md for the brand
tokens and owns the alert box's six-event accent language (gold/violet/pink — content, not
chrome; the standard has no purple and should not grow one, but they live in ONE file instead of
57 scattered literals).

It is a separate type because the renderers run on the frame-pump thread and must not touch
application resources. The duplication is made safe by OutputPaletteTests: it parses
Themes/Tokens.xaml and fails if any mirrored token drifts, and fails if a renderer reintroduces a
colour literal or "Segoe UI".

Ticker and flash glyphs now use the bundled Inter instead of Segoe UI. Neon red is the standard
live red — one red in the product, including the credit.

Fixed on the way: the palette's font fields were static pack-URI initialisers, which throw
TypeInitializationException in any host without a WPF Application (the test process caught it);
they are lazy now with a name fallback.

Services/Compositor/AlertTickerRenderer.cs

@@ -143,7 +143,7 @@ public static class AlertTickerRenderer
         const double padX = 16;
         const double gap = 8;
 
-        var font = new Typeface(new FontFamily("Segoe UI"), FontStyles.Normal, FontWeights.SemiBold, FontStretches.Normal);
+        var font = new Typeface(OutputPalette.Sans, FontStyles.Normal, FontWeights.SemiBold, FontStretches.Normal);
         var ft = new FormattedText(text, CultureInfo.InvariantCulture, FlowDirection.LeftToRight,
             font, 22, Brushes.White, 1.0);
 
@@ -156,7 +156,7 @@ public static class AlertTickerRenderer
         {
             var pill = new Rect(0, top, pillW, pillHeight);
             dc.DrawRoundedRectangle(new SolidColorBrush(Color.FromArgb(0xE6, 0x10, 0x13, 0x24)), null, pill, pillHeight / 2, pillHeight / 2);
-            dc.DrawRoundedRectangle(new SolidColorBrush(Color.FromRgb(0xe9, 0x45, 0x60)), null,
+            dc.DrawRoundedRectangle(new SolidColorBrush(OutputPalette.Live), null,
                 new Rect(padX, top + (pillHeight - 12) / 2.0, accentW, 12), 2, 2);
             dc.DrawText(ft, new Point(padX + accentW + gap, textTop));
         }