design: the code-set state colours now agree with the standard

Last inconsistency from the sweep: several VM-side state colours are still literals, and after
the palette moved they disagreed with everything around them — the top bar's LIVE state would
have painted the retired pink-red while the tile beside it used the standard red.

Values aligned (tokenisation of these sites is its own unit — they are strings bound to
Background/Foreground, so the fix is a VM->Brush refactor, not a find/replace):
- live / on-air / recorder dot: #e94560 -> #ff5451 (the standard red)
- error banner: #8f1f1f -> #93000a (error-container)
- audio meter bands follow the doc's stated thresholds: nominal cyan #38bdf8, caution amber
  #ffb95f, peak #ff5451 — they were green/yellow/red, which contradicted DESIGN.md's own table

GameMeterHonestyTests pinned the old band colours; its intent (the meter scales by volume) is
unchanged, so the two colour expectations now name the new bands.

ViewModels/MainViewModel.Streaming.Operations.cs

@@ -316,7 +316,7 @@ public partial class MainViewModel : ViewModelBase
             return;
         }
 
-        HealthIssueBackground = report.IsError ? "#8f1f1f" : "#b8860b";
+        HealthIssueBackground = report.IsError ? "#93000a" : "#b8860b";
         HealthIssueBanner = report.Text;
     }
 
@@ -486,8 +486,8 @@ public partial class MainViewModel : ViewModelBase
         var live = IsLive;
         // A live TEST broadcast wears gold, not the live red — the TEST badge +
         // gold are the "this is a rehearsal" cue (TASK 41).
-        TopBarBackground = live ? IsTestStream ? "#9c6f1c" : "#e94560" : "#16213e";
-        PreviewGlowBrush = live ? IsTestStream ? "#9c6f1c" : "#e94560" : "Transparent";
+        TopBarBackground = live ? IsTestStream ? "#9c6f1c" : "#ff5451" : "#16213e";
+        PreviewGlowBrush = live ? IsTestStream ? "#9c6f1c" : "#ff5451" : "Transparent";
         PreviewGlowThickness = live ? new Thickness(3) : new Thickness(0);
 
         if (!live) _healthPollTimer.Stop();