Fix legend hover not highlighting table row

legendMouseOver receives (chartContext, config), not three parameters.
The extra parameter was shifting config to undefined.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/views/reports/ReportsView.vue

@@ -358,7 +358,7 @@ const spendingChartOptions = computed(() => ({
       dataPointMouseLeave: () => {
         setChartHighlight(null)
       },
-      legendMouseOver: (_ctx: any, _opts: any, config: any) => {
+      legendMouseOver: (_ctx: any, config: any) => {
         const labels = spending.value?.categories.map(c => c.categoryName) ?? []
         setChartHighlight(labels[config.seriesIndex] ?? null)
       },