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/pkg/siteprobe/worker.go

@@ -0,0 +1,118 @@
+package siteprobe
+
+import (
+	"context"
+	"log"
+	"sync"
+	"time"
+
+	"ezops/model"
+
+	"gorm.io/gorm"
+)
+
+// Worker 站点拨测后台采集器 // Logan.Li
+type Worker struct {
+	db     *gorm.DB
+	stopCh chan struct{}
+	wg     sync.WaitGroup
+}
+
+// NewWorker 创建拨测 worker
+func NewWorker(db *gorm.DB) *Worker {
+	return &Worker{db: db, stopCh: make(chan struct{})}
+}
+
+// Start 启动拨测循环
+func (w *Worker) Start(intervalSec int) {
+	if intervalSec < 5 {
+		intervalSec = 10
+	}
+	w.wg.Add(1)
+	go func() {
+		defer w.wg.Done()
+		ticker := time.NewTicker(time.Duration(intervalSec) * time.Second)
+		defer ticker.Stop()
+		log.Printf("[SiteProbe] 拨测引擎启动，扫描间隔 %ds", intervalSec)
+		w.runOnce()
+		for {
+			select {
+			case <-ticker.C:
+				w.runOnce()
+			case <-w.stopCh:
+				log.Printf("[SiteProbe] 拨测引擎停止")
+				return
+			}
+		}
+	}()
+}
+
+// Stop 停止拨测
+func (w *Worker) Stop() {
+	close(w.stopCh)
+	w.wg.Wait()
+}
+
+// RunTaskNow 立即执行单个任务拨测 // Logan.Li
+func (w *Worker) RunTaskNow(taskID uint) error {
+	var task model.SiteTask
+	if err := w.db.First(&task, taskID).Error; err != nil {
+		return err
+	}
+	w.probeTask(task)
+	return nil
+}
+
+func (w *Worker) runOnce() {
+	var tasks []model.SiteTask
+	w.db.Where("status = ?", model.SiteTaskStatusRunning).Find(&tasks)
+	now := time.Now()
+	for _, task := range tasks {
+		if task.Frequency <= 0 {
+			task.Frequency = 60
+		}
+		if task.LastCheckAt != nil && now.Sub(*task.LastCheckAt) < time.Duration(task.Frequency)*time.Second {
+			continue
+		}
+		w.probeTask(task)
+	}
+}
+
+func (w *Worker) probeTask(task model.SiteTask) {
+	if task.TaskType == "" {
+		task.TaskType = model.SiteTaskType(inferTaskType(task))
+	}
+	outcome := Execute(context.Background(), task)
+	now := time.Now()
+
+	result := model.SiteResult{
+		TaskID:           task.ID,
+		Status:           outcome.Status,
+		HTTPStatusCode:   outcome.HTTPStatus,
+		ResponseTime:     outcome.ResponseTime,
+		TotalTime:        outcome.TotalTime,
+		RemoteIP:         outcome.RemoteIP,
+		ErrorMessage:     outcome.ErrorMessage,
+		SSLCertExpiry:    outcome.SSLCertExpiry,
+		SSLCertIssuer:    outcome.SSLCertIssuer,
+		SSLCertSubject:   outcome.SSLCertSubject,
+		SSLDaysRemaining: outcome.SSLDaysRemaining,
+		CheckedAt:        now,
+	}
+	w.db.Create(&result)
+
+	lastResult := "fail"
+	if outcome.Status == model.SiteResultSuccess {
+		lastResult = "success"
+	}
+	avg := outcome.ResponseTime
+	if task.AvgResponse > 0 {
+		avg = (task.AvgResponse + outcome.ResponseTime) / 2
+	}
+	w.db.Model(&model.SiteTask{}).Where("id = ?", task.ID).Updates(map[string]interface{}{
+		"task_type":    task.TaskType,
+		"last_result":  lastResult,
+		"last_check_at": now,
+		"avg_response": avg,
+	})
+}