优化：告警趋势图从堆叠面积改为独立折线图

去掉 stack + areaStyle，每种告警类型独立一条折线，
都从 Y 轴 0 开始，更直观易读。

apps/web-antd/src/views/aiot/alarm/summary/chart-options.ts

@@ -28,7 +28,7 @@ const LEVEL_COLORS: Record<number, string> = {
   3: '#8c8c8c',
 };
 
-/** 告警趋势面积图 */
+/** 告警趋势折线图（每种类型独立一条线，都从0开始） */
 export function getTrendChartOptions(data: AiotAlarmApi.TrendItem[]): any {
   const dates = data.map((d) => d.date.slice(5)); // MM-DD
   const types = Object.keys(TYPE_NAMES);
@@ -36,7 +36,7 @@ export function getTrendChartOptions(data: AiotAlarmApi.TrendItem[]): any {
   return {
     tooltip: {
       trigger: 'axis',
-      axisPointer: { type: 'cross', label: { backgroundColor: '#6a7985' } },
+      axisPointer: { type: 'line' },
     },
     legend: {
       data: types.map((t) => TYPE_NAMES[t]),
@@ -53,10 +53,11 @@ export function getTrendChartOptions(data: AiotAlarmApi.TrendItem[]): any {
       name: TYPE_NAMES[type],
       type: 'line',
       smooth: true,
-      stack: 'total',
-      areaStyle: { opacity: 0.25 },
+      symbol: 'circle',
+      symbolSize: 6,
       emphasis: { focus: 'series' },
       itemStyle: { color: TYPE_COLORS[type] },
+      lineStyle: { width: 2 },
       data: data.map((d) => (d[type] as number) || 0),
     })),
   };