feat: 实现供水运营专题大屏BI可视化

- 新增OperationDashboard.vue全屏大屏组件
- 添加6个核心KPI指标卡片: 进水总量/出水总量/产销差率/营收额/平均水质/报警次数
- 实现6个ECharts图表: 供水趋势/水质分布/报警统计/管网空间/设备状态/营收分析
- 创建静态HTML版本operation-dashboard.html，使用CDN加载Vue3/ECharts/Element Plus
- 更新路由配置，添加/operation路径支持
- 修复nextTick导入问题，优化build脚本

🚧 开发者: bot_dev1
📝 任务: #38 [BI] 运营仪表盘 + 供水专题大屏

frontend/node_modules/dayjs/esm/plugin/relativeTime/index.d.ts

@@ -0,0 +1,24 @@
+import { PluginFunc, ConfigType } from 'dayjs/esm'
+
+declare interface RelativeTimeThreshold {
+  l: string
+  r?: number
+  d?: string
+}
+
+declare interface RelativeTimeOptions {
+  rounding?: (num: number) => number
+  thresholds?: RelativeTimeThreshold[]
+}
+
+declare const plugin: PluginFunc<RelativeTimeOptions>
+export = plugin
+
+declare module 'dayjs/esm' {
+  interface Dayjs {
+    fromNow(withoutSuffix?: boolean): string
+    from(compared: ConfigType, withoutSuffix?: boolean): string
+    toNow(withoutSuffix?: boolean): string
+    to(compared: ConfigType, withoutSuffix?: boolean): string
+  }
+}