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/pages/monitor/site-monitor/SiteTaskDetailDialog.tsx

@@ -0,0 +1,42 @@
+// 拨测任务详情弹框 — 可观测指标与历史记录 // Logan.Li
+import {
+  Dialog, DialogContent, DialogDescription, DialogHeader, DialogTitle,
+} from '@/components/ui/dialog';
+import { Badge } from '@/components/ui/badge';
+import type { SiteTask } from './helpers';
+import { fmtFrequency, normalizeProbeType } from './helpers';
+import { SiteResultsPanel } from './SiteResultsPanel';
+
+const dialogClass =
+  '!max-w-[min(96vw,88rem)] sm:!max-w-[min(96vw,88rem)] w-[min(96vw,88rem)] max-h-[92vh] flex flex-col gap-2 p-4 sm:p-5 bg-[var(--dg-bg-primary)] border-[var(--dg-border)] overflow-hidden';
+
+interface Props {
+  task: SiteTask | null;
+  open: boolean;
+  onOpenChange: (open: boolean) => void;
+  onProbed: () => void;
+}
+
+export function SiteTaskDetailDialog({ task, open, onOpenChange, onProbed }: Props) {
+  if (!task) return null;
+
+  const probeType = normalizeProbeType(task.type);
+
+  return (
+    <Dialog open={open} onOpenChange={onOpenChange}>
+      <DialogContent className={dialogClass}>
+        <DialogHeader className="shrink-0 space-y-1 pr-8">
+          <DialogTitle className="text-base truncate">{task.name}</DialogTitle>
+          <DialogDescription className="flex flex-wrap items-center gap-2 text-xs">
+            <span className="truncate max-w-full font-mono text-[var(--dg-text-muted)]">{task.url}</span>
+            <Badge variant="outline" className="text-[10px]">{probeType}</Badge>
+            <span className="text-[var(--dg-text-muted)]">频率 {fmtFrequency(task.frequency_sec)}</span>
+          </DialogDescription>
+        </DialogHeader>
+        <div className="flex-1 min-h-0 overflow-y-auto">
+          <SiteResultsPanel task={task} onProbed={onProbed} embedded />
+        </div>
+      </DialogContent>
+    </Dialog>
+  );
+}