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/@cesium/engine/Source/DataSources/getElement.js

@@ -0,0 +1,26 @@
+import DeveloperError from "../Core/DeveloperError.js";
+
+/**
+ * If element is a string, look up the element in the DOM by ID.  Otherwise return element.
+ *
+ * @private
+ *
+ * @exception {DeveloperError} Element with id "id" does not exist in the document.
+ */
+function getElement(element) {
+  if (typeof element === "string") {
+    const foundElement = document.getElementById(element);
+
+    //>>includeStart('debug', pragmas.debug);
+    if (foundElement === null) {
+      throw new DeveloperError(
+        `Element with id "${element}" does not exist in the document.`,
+      );
+    }
+    //>>includeEnd('debug');
+
+    element = foundElement;
+  }
+  return element;
+}
+export default getElement;