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/lodash-es/once.js

@@ -0,0 +1,25 @@
+import before from './before.js';
+
+/**
+ * Creates a function that is restricted to invoking `func` once. Repeat calls
+ * to the function return the value of the first invocation. The `func` is
+ * invoked with the `this` binding and arguments of the created function.
+ *
+ * @static
+ * @memberOf _
+ * @since 0.1.0
+ * @category Function
+ * @param {Function} func The function to restrict.
+ * @returns {Function} Returns the new restricted function.
+ * @example
+ *
+ * var initialize = _.once(createApplication);
+ * initialize();
+ * initialize();
+ * // => `createApplication` is invoked once
+ */
+function once(func) {
+  return before(2, func);
+}
+
+export default once;