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/echarts-liquidfill/.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,16 @@
+<!--
+Paste your code here if you have a specific question.
+-->
+```js
+var option = {
+    series: [{
+        type: 'liquidFill',
+        data: [0.6]
+    }]
+};
+```
+
+<!--
+Fork http://gallery.echartsjs.com/editor.html?c=xr1XplzB4e and reproduce your
+problem, and paste the URL here to help us understand your question.
+-->