Replace built-in chart legend with custom legend for reliable hover sync

ApexCharts legendMouseOver event is unreliable for donut charts. Use custom
HTML legend items with direct mouseenter/mouseleave handlers that sync
highlighting between legend, chart slices, and the category table.

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

frontend/src/views/reports/ReportsView.vue

@@ -86,6 +86,19 @@
                   :options="spendingChartOptions"
                   :series="spendingChartSeries"
                 />
+                <div v-if="spending.categories.length > 0" class="d-flex flex-wrap justify-center ga-2 mt-2">
+                  <div
+                    v-for="(cat, idx) in spending.categories"
+                    :key="cat.categoryName"
+                    class="d-flex align-center ga-1 px-2 py-1 rounded cursor-pointer legend-item"
+                    :class="{ 'spending-row-highlight': highlightedCategory === cat.categoryName }"
+                    @mouseenter="highlightCategory(cat.categoryName)"
+                    @mouseleave="unhighlightCategory()"
+                  >
+                    <span class="legend-dot" :style="{ backgroundColor: chartColors[idx % chartColors.length] }" />
+                    <span class="text-caption">{{ cat.categoryName }}</span>
+                  </div>
+                </div>
                 <div v-else class="text-center pa-8 text-medium-emphasis">No spending data for this period</div>
               </v-col>
               <v-col cols="12" md="7">
@@ -347,6 +360,8 @@ function setChartHighlight(categoryName: string | null) {
   }
 }
 
+const chartColors = ['#008FFB', '#00E396', '#FEB019', '#FF4560', '#775DD0', '#546E7A', '#26a69a', '#D10CE8', '#2E93fA', '#FF9800']
+
 const spendingChartOptions = computed(() => ({
   chart: {
     type: 'donut' as const,
@@ -358,17 +373,11 @@ const spendingChartOptions = computed(() => ({
       dataPointMouseLeave: () => {
         setChartHighlight(null)
       },
-      legendMouseOver: (_ctx: any, config: any) => {
-        const labels = spending.value?.categories.map(c => c.categoryName) ?? []
-        setChartHighlight(labels[config.seriesIndex] ?? null)
-      },
-      legendMouseOut: () => {
-        setChartHighlight(null)
-      },
     },
   },
+  colors: chartColors,
   labels: spending.value?.categories.map(c => c.categoryName) ?? [],
-  legend: { position: 'bottom' as const, labels: { colors: labelColor.value } },
+  legend: { show: false },
   dataLabels: { style: { colors: ['#FFFFFF'] }, dropShadow: { enabled: true, top: 1, left: 1, blur: 2, opacity: 0.5 } },
   tooltip: {
     y: {
@@ -589,4 +598,13 @@ onMounted(async () => {
   background-color: rgba(var(--v-theme-primary), 0.15);
   transition: background-color 0.15s;
 }
+.legend-dot {
+  width: 10px;
+  height: 10px;
+  border-radius: 50%;
+  flex-shrink: 0;
+}
+.legend-item {
+  transition: background-color 0.15s;
+}
 </style>