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>

frontend/src/locales/en-US.json

@@ -195,12 +195,28 @@
     "stat": {
       "servers": "Servers",
       "running": "Running",
+      "cronJobs": "Cron Jobs",
+      "siteProbes": "Site Probes",
+      "kubernetes": "Kubernetes",
       "k8sClusters": "K8s Clusters",
       "healthyClusters": "Healthy",
       "alerts": "Alerts",
       "critical": "Critical",
       "monthlyCost": "Monthly Cost"
     },
+    "ops": {
+      "title": "Ops Overview",
+      "description": "Assets, monitoring & task shortcuts",
+      "monitorScreen": "Monitor Screen",
+      "servers": "Servers",
+      "domains": "Domains",
+      "hostMonitor": "Host Monitor",
+      "cronJobs": "Cron Jobs",
+      "siteProbes": "Site Probes",
+      "middleware": "Middleware",
+      "todayExecutions": "Executions Today",
+      "firingAlerts": "Firing Alerts"
+    },
     "alerts": {
       "title": "Alert Messages",
       "description": "Recently triggered alert events",
@@ -250,6 +266,8 @@
       "error": "Error",
       "nodes": "Nodes",
       "pods": "Pods",
+      "ingress": "Ingress",
+      "deployments": "Deployments",
       "cpu": "CPU",
       "memory": "Memory"
     },