fix(charts): migrate ECharts 6 containLabel and hide redundant pie legend

- Replace `containLabel: true` with `outerBoundsMode: 'same'` in
  EChartLine, EChartBar, EChartHeatmap to suppress the ECharts 6
  deprecation warning; `outerBoundsMode: 'same'` is the semantic
  equivalent (outer boundary equals the grid rect, labels fit inside)
- In EChartPie, auto-hide the right-side legend when outer labels
  (indicator lines + text) are already visible, and center the chart
  accordingly to avoid redundant information

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

src/components/charts/EChartBar.vue

@@ -68,7 +68,7 @@ const option = computed<EChartsOption>(() => {
       right: 16,
       top: 20,
       bottom: isHorizontal ? 20 : labelCount > 8 ? 48 : 30,
-      containLabel: true,
+      outerBoundsMode: 'same',
     },
     xAxis: isHorizontal
       ? {

src/components/charts/EChartHeatmap.vue

@@ -68,7 +68,7 @@ const option = computed<EChartsOption>(() => {
       right: 20,
       top: isCompact ? 12 : 24,
       bottom: isCompact ? 52 : 70,
-      containLabel: true,
+      outerBoundsMode: 'same',
     },
     xAxis: {
       type: 'category',

src/components/charts/EChartLine.vue

@@ -110,7 +110,7 @@ const option = computed<EChartsOption>(() => {
       right: 20,
       top: hasSeries ? (isCompact ? 44 : 56) : 20,
       bottom: useDataZoom ? 66 : 34,
-      containLabel: true,
+      outerBoundsMode: 'same',
     },
     legend: hasSeries
       ? {

src/components/charts/EChartPie.vue

@@ -81,6 +81,7 @@ const option = computed<EChartsOption>(() => {
         },
       }
   const showOuterLabel = !isCompact && !isDense
+  const effectiveShowLegend = props.showLegend && !showOuterLabel
 
   return {
     color: colors,
@@ -95,12 +96,16 @@ const option = computed<EChartsOption>(() => {
         color: '#fff',
       },
     },
-    legend: props.showLegend ? legendPlacement : undefined,
+    legend: effectiveShowLegend ? legendPlacement : undefined,
     series: [
       {
         type: 'pie',
         radius: props.doughnut ? [props.innerRadius, isCompact ? '58%' : '68%'] : isCompact ? '58%' : '68%',
-        center: props.showLegend ? (isCompact ? ['50%', '42%'] : ['38%', '50%']) : ['50%', isCompact ? '46%' : '50%'],
+        center: effectiveShowLegend
+          ? isCompact
+            ? ['50%', '42%']
+            : ['38%', '50%']
+          : ['50%', isCompact ? '46%' : '50%'],
         avoidLabelOverlap: true,
         itemStyle: {
           borderRadius: 4,