feat(visualizer): add build overlay toggle

Default is off so candles match production; enable via the new Build button when needed.

apps/visualizer/src/features/chart/ChartPanel.tsx

@@ -18,6 +18,8 @@ type Props = {
   onTimeframeChange: (tf: string) => void;
   showIndicators: boolean;
   onToggleIndicators: () => void;
+  showBuild: boolean;
+  onToggleBuild: () => void;
   seriesLabel: string;
 };
 
@@ -49,6 +51,8 @@ export default function ChartPanel({
   onTimeframeChange,
   showIndicators,
   onToggleIndicators,
+  showBuild,
+  onToggleBuild,
   seriesLabel,
 }: Props) {
   const [isFullscreen, setIsFullscreen] = useState(false);
@@ -272,6 +276,8 @@ export default function ChartPanel({
             onTimeframeChange={onTimeframeChange}
             showIndicators={showIndicators}
             onToggleIndicators={onToggleIndicators}
+            showBuild={showBuild}
+            onToggleBuild={onToggleBuild}
             priceAutoScale={priceAutoScale}
             onTogglePriceAutoScale={() => setPriceAutoScale((v) => !v)}
             seriesLabel={seriesLabel}
@@ -300,6 +306,7 @@ export default function ChartPanel({
               ema20={indicators.ema20}
               bb20={indicators.bb20}
               showIndicators={showIndicators}
+              showBuild={showBuild}
               bucketSeconds={bucketSeconds}
               seriesKey={seriesKey}
               fib={fibRenderable}