fix: replace addEventListener with onmouseleave to prevent listener leak

web/components/ChartCard/TableViz.tsx

@@ -42,7 +42,7 @@ export default function TableViz({ config, rows, onEdit, onDelete }: Props) {
                 <th className="text-right px-2 py-1 text-green-400">Green</th>
               )}
               {config.signal_type !== 'green' && (
-                <th className="text-right px-2 py-1 text-red-400">Red</th>
+                <th className="text-right px-2 py-1 text-red-400">Red (NP)</th>
               )}
             </tr>
           </thead>

web/components/ChartCard/usePlot.ts

@@ -57,11 +57,11 @@ export function usePlot(
 
       // Defer mouseleave — prevents React hydration events firing before lastIdxRef set
       requestAnimationFrame(() => {
-        plot.over.addEventListener('mouseleave', () => {
+        plot.over.onmouseleave = () => {
           const p = plotRef.current;
           if (!p) return;
           p.setCursor({ left: idxToPixel(p, lastIdxRef.current), top: -10 });
-        });
+        };
       });
     }
     // deps is intentionally dynamic — passed by parent to allow external rebuild triggers