feat: 云账号编辑功能 + 通知渠道种子数据 + 修复mock.go编译错误

- 新增 PUT /cloud-accounts/:id 后端端点（UpdateCloudAccount handler + 路由注册）
- 前端 CloudAccountManager 添加编辑弹窗：复用创建表单，凭证留空保持不变
- 修复 scripts/mock.go 编译错误：补充缺失的 generateNotifyChannels 函数（5种通知渠道种子）
- 包含前序未提交的告警通知渠道 CRUD 后端API + AlertManager 通知配置前端UI

backend/internal/api/routes/routes.go

@@ -93,6 +93,7 @@ func Register(r *gin.Engine, db *gorm.DB, log *zap.Logger, cfg *config.Config) {
 	{
 		cloudAccounts.GET("", cloudAccountHandler.ListCloudAccounts)
 		cloudAccounts.POST("", cloudAccountHandler.CreateCloudAccount)
+		cloudAccounts.PUT("/:id", cloudAccountHandler.UpdateCloudAccount)
 		cloudAccounts.DELETE("/:id", cloudAccountHandler.DeleteCloudAccount)
 	}
 
@@ -132,6 +133,11 @@ func Register(r *gin.Engine, db *gorm.DB, log *zap.Logger, cfg *config.Config) {
 		alerts.DELETE("/rules/:id", alertHandler.DeleteRule)
 		alerts.POST("/rules/:id/toggle", alertHandler.ToggleRule)
 		alerts.POST("/:id/ack", alertHandler.AcknowledgeAlert)
+		alerts.GET("/notify-channels", alertHandler.ListNotifyChannels)
+		alerts.POST("/notify-channels", alertHandler.CreateNotifyChannel)
+		alerts.PUT("/notify-channels/:id", alertHandler.UpdateNotifyChannel)
+		alerts.DELETE("/notify-channels/:id", alertHandler.DeleteNotifyChannel)
+		alerts.POST("/notify-channels/:id/test", alertHandler.TestNotifyChannel)
 	}
 
 	// 流水线路由