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/postcss/lib/stringifier.d.ts

@@ -0,0 +1,45 @@
+import {
+  AnyNode,
+  AtRule,
+  Builder,
+  Comment,
+  Container,
+  Declaration,
+  Document,
+  Root,
+  Rule
+} from './postcss.js'
+
+declare namespace Stringifier {
+  export { Stringifier_ as default }
+}
+
+declare class Stringifier_ {
+  builder: Builder
+  constructor(builder: Builder)
+  atrule(node: AtRule, semicolon?: boolean): void
+  beforeAfter(node: AnyNode, detect: 'after' | 'before'): string
+  block(node: AnyNode, start: string): void
+  body(node: Container): void
+  comment(node: Comment): void
+  decl(node: Declaration, semicolon?: boolean): void
+  document(node: Document): void
+  raw(node: AnyNode, own: null | string, detect?: string): boolean | string
+  rawBeforeClose(root: Root): string | undefined
+  rawBeforeComment(root: Root, node: Comment): string | undefined
+  rawBeforeDecl(root: Root, node: Declaration): string | undefined
+  rawBeforeOpen(root: Root): string | undefined
+  rawBeforeRule(root: Root): string | undefined
+  rawColon(root: Root): string | undefined
+  rawEmptyBody(root: Root): string | undefined
+  rawIndent(root: Root): string | undefined
+  rawSemicolon(root: Root): boolean | undefined
+  rawValue(node: AnyNode, prop: string): number | string
+  root(node: Root): void
+  rule(node: Rule): void
+  stringify(node: AnyNode, semicolon?: boolean): void
+}
+
+declare class Stringifier extends Stringifier_ {}
+
+export = Stringifier