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.cs

@@ -87,10 +87,10 @@ public partial class MainViewModel : ViewModelBase
     public bool IsOffline => StreamStatus == StreamStatus.Offline;
     public bool IsLive => StreamStatus == StreamStatus.Streaming;
     public bool IsLivePrivate => IsLive && string.Equals(StreamVisibility, "Private", StringComparison.OrdinalIgnoreCase);
-    public string RecDotBrush => !IsRecording ? "#555555" : "#e94560";
+    public string RecDotBrush => !IsRecording ? "#555555" : "#ff5451";
     public string RecTextBrush => (IsLive || IsRecording) ? "#ffffff" : "#888888";
     public double RecDotOpacity => IsRecording ? _recDotPulse : 0.55;
-    public string OnAirBrush => !IsLive ? "#555555" : IsLivePrivate ? "#22c55e" : "#e94560";
+    public string OnAirBrush => !IsLive ? "#555555" : IsLivePrivate ? "#22c55e" : "#ff5451";
 
     // ─── REC / ON-AIR pills (TASK 18) ───
     public bool RecordPillOn
@@ -222,7 +222,7 @@ public partial class MainViewModel : ViewModelBase
     /// <summary>Reality dot color, one meaning per mode: gold = test, red = live,
     /// green = recording. The pre-spec pulsing lamp never shipped; the word + bar
     /// color carry the state and the dot just pins it.</summary>
-    public string RunningDotBrush => IsTestStream ? "#9c6f1c" : IsLive ? "#e94560" : "#22c55e";
+    public string RunningDotBrush => IsTestStream ? "#9c6f1c" : IsLive ? "#ff5451" : "#22c55e";
 
     /// <summary>Raises every flag the top bar renders, so any state change re-renders
     /// exactly the world that is now true.</summary>