feat(bar-app): retune subscription card palette for the dark theme

Replace the raw system green/yellow/orange/red headroom colors (garish on the
dark surface and colliding with the brand orange) with a muted, intuitive
green-amber-coral-red palette that leans coral for 'low' so a near-empty
window never reads as the accent. Drop the cool indigo card wash for a neutral
elevated surface so the warm bars no longer clash; subscription identity stays
on the section header and badge.

macos-bar/Sources/CCSBarApp/BarSubscriptionCard.swift

@@ -36,7 +36,7 @@ struct BarSubscriptionCard: View {
     .padding(.horizontal, 10)
     .frame(maxWidth: .infinity, alignment: .leading)
     .background(
-      BarTheme.subscription.opacity(0.07),
+      BarTheme.cardSurface,
       in: RoundedRectangle(cornerRadius: 9))
   }
 
@@ -53,7 +53,7 @@ struct BarSubscriptionCard: View {
         .font(.system(.body, design: .default).weight(.semibold))
         .lineLimit(1)
       if row.needsReauth {
-        Chip("reauth", tint: .red)
+        Chip("reauth", tint: BarTheme.bandRed)
       }
       Spacer(minLength: 4)
       if let tier = row.tier {
@@ -149,7 +149,7 @@ struct BarSubscriptionCard: View {
       if isAtRisk, let pace = paceWarningText(for: w) {
         Text(pace)
           .font(.system(.caption2, design: .monospaced))
-          .foregroundStyle(.orange)
+          .foregroundStyle(BarTheme.bandCoral)
           .lineLimit(1)
           .padding(.leading, 5)
       }
@@ -244,18 +244,18 @@ struct BarSubscriptionCard: View {
 
   private var healthColor: Color {
     switch row.health {
-    case "error": return .red
-    case "warning": return .orange
-    default: return .green
+    case "error": return BarTheme.bandRed
+    case "warning": return BarTheme.bandAmber
+    default: return BarTheme.bandGreen
     }
   }
 
   private func color(for band: BarQuotaGauge.Band) -> Color {
     switch band {
-    case .green: return .green
-    case .yellow: return .yellow
-    case .orange: return .orange
-    case .red: return .red
+    case .green: return BarTheme.bandGreen
+    case .yellow: return BarTheme.bandAmber
+    case .orange: return BarTheme.bandCoral
+    case .red: return BarTheme.bandRed
     case .none: return .secondary
     }
   }

macos-bar/Sources/CCSBarApp/Sparkline.swift

@@ -29,4 +29,17 @@ enum BarTheme {
   /// so the user's own plan reads apart from CLIProxy pool accounts. A cool indigo
   /// contrasts with the warm orange accent used for everything else.
   static let subscription = Color(red: 0.357, green: 0.388, blue: 0.851) // ~#5B63D9
+
+  /// Headroom palette for quota bars. Muted for the dark surface (raw system
+  /// green/yellow/orange/red read garish here) and intuitive green→amber→coral→red.
+  /// Deliberately leans coral/red for "low" rather than the brand orange, so a
+  /// nearly-empty window never gets mistaken for the accent.
+  static let bandGreen = Color(red: 0.36, green: 0.74, blue: 0.56) // ~#5CBC8F emerald
+  static let bandAmber = Color(red: 0.86, green: 0.67, blue: 0.31) // ~#DBAB4F gold
+  static let bandCoral = Color(red: 0.91, green: 0.46, blue: 0.36) // ~#E8755C warning
+  static let bandRed = Color(red: 0.85, green: 0.34, blue: 0.31) // ~#D9564F critical
+
+  /// Neutral elevated surface for the subscription card — a faint light lift
+  /// rather than a colored wash, so the warm headroom bars read cleanly on top.
+  static let cardSurface = Color.primary.opacity(0.05)
 }