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/package.json

@@ -10,7 +10,9 @@
     "preview": "vite preview"
   },
   "dependencies": {
+    "@codemirror/lang-python": "^6.2.1",
     "@codemirror/lang-yaml": "^6.1.3",
+    "@codemirror/legacy-modes": "^6.5.3",
     "@codemirror/state": "^6.6.0",
     "@codemirror/theme-one-dark": "^6.1.3",
     "@codemirror/view": "^6.43.1",
@@ -60,9 +62,11 @@
     "react-dom": "^19.2.0",
     "react-hook-form": "^7.70.0",
     "react-i18next": "^17.0.8",
+    "react-markdown": "^10.1.0",
     "react-resizable-panels": "^4.2.2",
     "react-router-dom": "^7.13.2",
     "recharts": "^2.15.4",
+    "remark-gfm": "^4.0.1",
     "sonner": "^2.0.7",
     "tailwind-merge": "^3.4.0",
     "vaul": "^1.1.2",