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/flattenDeep.js

@@ -0,0 +1,25 @@
+var baseFlatten = require('./_baseFlatten');
+
+/** Used as references for various `Number` constants. */
+var INFINITY = 1 / 0;
+
+/**
+ * Recursively flattens `array`.
+ *
+ * @static
+ * @memberOf _
+ * @since 3.0.0
+ * @category Array
+ * @param {Array} array The array to flatten.
+ * @returns {Array} Returns the new flattened array.
+ * @example
+ *
+ * _.flattenDeep([1, [2, [3, [4]], 5]]);
+ * // => [1, 2, 3, 4, 5]
+ */
+function flattenDeep(array) {
+  var length = array == null ? 0 : array.length;
+  return length ? baseFlatten(array, INFINITY) : [];
+}
+
+module.exports = flattenDeep;