feat: 监控告警体系统一重构 + 自动化任务调度引擎 + 监控大屏拆分

告警中心
- 新增统一告警(alert_unified)、监控告警规则(monitor_alert_rule)、指标目录(alert_metric_catalog)
- 通知策略与消息分发(alert_notify_policy/dispatch/message)、静默规则
- 告警引擎按阈值/SNMP 拆分(alert_engine_monitor/snmp)

监控采集
- SNMP 常量/模板与历史指标(snmp templates/constants、snmp_metrics_history、snmp_collect)
- 中间件监控 Redis 采集与种子(middleware_monitor_redis/seed)
- 站点探测 pkg(siteprobe) + 站点视图(site_view)

自动化任务
- cron 调度器(cronscheduler)、脚本运行器(scriptrunner)、系统任务(systask)及运行记录(cron_job_run、system_task)

审计与凭证
- 审计设置(audit_setting) + 历史清理(auditcleaner)

前端
- 监控页面(host/middleware/site/snmp)拆分为子模块并大屏化
- 告警中心多 Tab(规则/指标目录/通知策略/静默)、任务管理组件重构、Agent CLI Markdown 渲染
- 移除旧脚本卡片/详情/日志组件，统一为 ScriptTable/ScriptCodeEditor/TerminalOutput

Co-Authored-By: Claude <noreply@anthropic.com>

backend/controller/user_admin.go

@@ -249,6 +249,56 @@ func (h *UserHandler) DeleteUser(c *gin.Context) {
 	})
 }
 
+// BatchDeleteUsers 批量删除用户 // Logan.Li
+// POST /api/v1/admin/users/batch-delete
+func (h *UserHandler) BatchDeleteUsers(c *gin.Context) {
+	var req model.IDsRequest
+	if err := c.ShouldBindJSON(&req); err != nil || len(req.IDs) == 0 {
+		c.JSON(http.StatusBadRequest, model.Response{Code: 400, Message: "请提供要删除的用户 ID 列表"})
+		return
+	}
+
+	currentUID, _ := c.Get("userID")
+	currentID, _ := currentUID.(uint)
+
+	deleted := 0
+	skipped := 0
+	var skippedNames []string
+
+	for _, id := range req.IDs {
+		if uint(id) == currentID {
+			skipped++
+			skippedNames = append(skippedNames, "当前登录用户")
+			continue
+		}
+		var user model.User
+		if err := h.db.First(&user, id).Error; err != nil {
+			skipped++
+			continue
+		}
+		if user.IsAdmin {
+			skipped++
+			skippedNames = append(skippedNames, user.Username)
+			continue
+		}
+		if err := h.db.Delete(&user).Error; err != nil {
+			skipped++
+			continue
+		}
+		deleted++
+	}
+
+	msg := fmt.Sprintf("已删除 %d 个用户", deleted)
+	if skipped > 0 {
+		msg += fmt.Sprintf("，跳过 %d 个", skipped)
+	}
+	c.JSON(http.StatusOK, model.Response{
+		Code:    200,
+		Message: msg,
+		Data:    gin.H{"deleted": deleted, "skipped": skipped, "skipped_names": skippedNames},
+	})
+}
+
 // BatchImportUsers 批量导入用户
 // POST /api/v1/admin/users/batch-import
 func (h *UserHandler) BatchImportUsers(c *gin.Context) {