fix: explicitly reset legend symbols when switching from SKU to other groupings

Highcharts merges options on update, so symbolWidth:0 persisted
when navigating from SKU to user/model. Now always set legend
symbol values explicitly (0 for SKU, undefined for others) so
Highcharts falls back to its defaults on non-SKU views.

Author: austenstone

src/components/charts/CostBreakdownChart.tsx

@@ -102,7 +102,9 @@ export function CostBreakdownChart({ stackField = 'model', metricOptions }: Cost
           : '<tr style="border-top: 1px solid var(--borderColor-muted, #d1d9e0b3);"><td><b>Total:&nbsp;</b></td><td style="text-align: right;"><b>{point.total:,.0f}</b></td></tr></table>',
       },
       plotOptions: { column: { stacking: 'normal' } },
-      ...(stackField === 'sku' && { legend: { symbolWidth: 0, symbolHeight: 0, symbolPadding: 0 } }),
+      legend: stackField === 'sku'
+        ? { symbolWidth: 0, symbolHeight: 0, symbolPadding: 0 }
+        : { symbolWidth: undefined, symbolHeight: undefined, symbolPadding: undefined },
       series,
     };
   }, [activeReport, timeBucket, visibleRows, stackField, activeMetric, dataField]);

src/components/charts/ModelBreakdownChart.tsx

@@ -174,7 +174,9 @@ export function GroupBreakdownChart({ stackField = 'model', metricOptions }: Gro
           : '<tr style="border-top: 1px solid var(--borderColor-muted, #d1d9e0b3);"><td><b>Total:&nbsp;</b></td><td style="text-align: right;"><b>{point.total:,.0f}</b></td></tr></table>',
       },
       plotOptions: { bar: { stacking: 'normal' } },
-      ...(stackField === 'sku' && { legend: { symbolWidth: 0, symbolHeight: 0, symbolPadding: 0 } }),
+      legend: stackField === 'sku'
+        ? { symbolWidth: 0, symbolHeight: 0, symbolPadding: 0 }
+        : { symbolWidth: undefined, symbolHeight: undefined, symbolPadding: undefined },
       series,
     };
   }, [activeReport, groupByColumn, stackField, visibleRows, hiddenGroups, toggleGroup, activeMetric, dataField]);

src/components/charts/TimeSeriesChart.tsx

@@ -180,7 +180,9 @@ export function TimeSeriesChart({ metricOptions }: { metricOptions?: MetricOptio
             },
       },
       series,
-      ...(groupByColumn === 'sku' && { legend: { symbolWidth: 0, symbolHeight: 0, symbolPadding: 0 } }),
+      legend: groupByColumn === 'sku'
+        ? { symbolWidth: 0, symbolHeight: 0, symbolPadding: 0 }
+        : { symbolWidth: undefined, symbolHeight: undefined, symbolPadding: undefined },
       chart: { height: 400 },
     };
   }, [activeReport, groupByColumn, timeBucket, visibleRows, lineMode, rollingWindow, dataField, activeMetric]);