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)

backend/scripts/mock.go

@@ -70,6 +70,9 @@ func generateMockData(db *gorm.DB) error {
 	if err := generateNavigations(db); err != nil {
 		return err
 	}
+	if err := generateBillings(db); err != nil {
+		return err
+	}
 	return nil
 }
 
@@ -564,6 +567,73 @@ func generateNavigations(db *gorm.DB) error {
 	return nil
 }
 
+func generateBillings(db *gorm.DB) error {
+	accounts := []struct {
+		ID       uint
+		Name     string
+		Provider string
+	}{
+		{1, "阿里云主账号", "aliyun"},
+		{2, "腾讯云生产环境", "tencent"},
+		{3, "AWS海外业务", "aws"},
+		{4, "华为云政务云", "huawei"},
+	}
+
+	services := map[string][]string{
+		"aliyun":  {"ECS云服务器", "RDS数据库", "OSS对象存储", "SLB负载均衡", "CDN加速"},
+		"tencent": {"CVM云服务器", "CDB数据库", "COS对象存储", "CLB负载均衡", "CDN加速"},
+		"aws":     {"EC2", "RDS", "S3", "CloudFront", "Lambda"},
+		"huawei":  {"ECS弹性云服务器", "RDS数据库", "OBS对象存储", "ELB弹性负载均衡"},
+	}
+
+	now := time.Now()
+	var billings []models.CloudBilling
+
+	// 生成最近60天每天的账单
+	for day := 59; day >= 0; day-- {
+		date := now.AddDate(0, 0, -day).Format("2006-01-02")
+		for _, acc := range accounts {
+			// 每个账号每天 1-3 条记录（不同服务）
+			svcs := services[acc.Provider]
+			count := 1 + rand.Intn(3)
+			for i := 0; i < count; i++ {
+				svc := svcs[rand.Intn(len(svcs))]
+				cost := 50 + rand.Float64()*500
+				billings = append(billings, models.CloudBilling{
+					CloudAccountID: &acc.ID,
+					AccountName:    acc.Name,
+					Provider:       acc.Provider,
+					BillingDate:    date,
+					Cost:           cost,
+					Currency:       "CNY",
+					Service:        svc,
+				})
+			}
+		}
+	}
+
+	for i := range billings {
+		if err := db.Create(&billings[i]).Error; err != nil {
+			// skip duplicates
+			continue
+		}
+	}
+	fmt.Println("Generated cloud billings:", len(billings))
+
+	// 生成预警规则
+	rules := []models.BillingAlertRule{
+		{Name: "每日总成本超500元", Metric: "daily", Threshold: 500, Operator: ">", Enabled: true},
+		{Name: "阿里云日费用超300元", Provider: "aliyun", Metric: "daily", Threshold: 300, Operator: ">", Enabled: true},
+		{Name: "月度总成本超1万元", Metric: "monthly", Threshold: 10000, Operator: ">", Enabled: true},
+	}
+	for i := range rules {
+		db.Create(&rules[i])
+	}
+	fmt.Println("Generated billing alert rules:", len(rules))
+
+	return nil
+}
+
 func randomString(length int) string {
 	const charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
 	b := make([]byte, length)