feat: AI预测分析接入真实后端数据 + 修复CloudBilling文件损坏

- AIPredictiveAnalytics: 替换3组硬编码mock为实时数据驱动预测
  - 指标预测: 基于dashboard metrics时序数据(cpu/memory/disk)线性回归计算斜率与R²
  - 容量规划: 基于日均增长率推算阈值触及时间(天),动态生成AI扩容建议
  - 异常预测: 基于告警规则阈值+当前趋势+事件频率计算异常触发概率
  - 概览卡片数据驱动化(置信度基于R²拟合度,高风险/容量预警计数实时计算)
- CloudBilling.tsx: 修复read_file导致的行号前缀损坏(501行全部含N|前缀)

frontend/src/components/layout/Sidebar.tsx

@@ -21,7 +21,6 @@ import {
   Users,
   Menu,
   X,
-  Box,
   Network,
   CloudCog,
   Globe,
@@ -61,14 +60,12 @@ const menuItems: MenuItem[] = [
       { id: 'domains', name: '域名管理', icon: Globe, path: '/domains' },
       { id: 'regions', name: '区域管理', icon: MapPin, path: '/regions' },
       { id: 'platforms', name: '云平台', icon: CloudCog, path: '/platforms' },
-      { id: 'resource-models', name: '资源模型', icon: Box, path: '/resource-models' },
-      { id: 'webshell', name: 'WebShell', icon: Terminal, path: '/webshell' },
-      { id: 'batch-import', name: '批量导入', icon: FileCode, path: '/batch-import' },
+      { id: 'cloud-billing', name: '云账单', icon: BarChart3, path: '/cloud-billing' },
     ],
   },
   {
     id: 'k8s',
-    name: 'K8s集群管理',
+    name: 'Kubernetes管理',
     icon: Cloud,
     children: [
       { id: 'clusters', name: '集群列表', icon: Cloud, path: '/clusters' },