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/components/system/SystemUserTab.tsx

@@ -22,6 +22,7 @@ import {
   Edit,
   Trash2,
 } from 'lucide-react';
+import { Checkbox } from '@/components/ui/checkbox';
 import { UserFormDialog, type UserFormData } from './UserFormDialog';
 import { UserDetailDialog } from './UserDetailDialog';
 import { CsvImportDialog } from './CsvImportDialog';
@@ -49,6 +50,9 @@ interface SystemUserTabProps {
   openCreate: () => void;
   openEdit: ( user: any) => void;
   handleDelete: ( user: any) => void;
+  handleBatchDelete: () => void;
+  selectedUserIds: number[];
+  setSelectedUserIds: React.Dispatch<React.SetStateAction<number[]>>;
   onResetPassword?: (user: any) => void;
   // CSV import
   importDialogOpen: 'csv' | 'ldap' | null;
@@ -91,6 +95,9 @@ export function SystemUserTab({
   openCreate,
   openEdit,
   handleDelete,
+  handleBatchDelete,
+  selectedUserIds,
+  setSelectedUserIds,
   onResetPassword,
   importDialogOpen,
   setImportDialogOpen,
@@ -113,6 +120,19 @@ export function SystemUserTab({
   setLdapUsers,
 }: SystemUserTabProps) {
   const { hasPermission } = usePermission();
+  const canManage = hasPermission('system:user');
+
+  const toggleSelect = (id: number) => {
+    setSelectedUserIds((prev) =>
+      prev.includes(id) ? prev.filter((i) => i !== id) : [...prev, id],
+    );
+  };
+
+  const allSelected = filteredUsers.length > 0 && selectedUserIds.length === filteredUsers.length;
+  const toggleSelectAll = () => {
+    setSelectedUserIds(allSelected ? [] : filteredUsers.map((u) => u.id));
+  };
+
   return (
     <>
       {/* Filters */}
@@ -148,6 +168,23 @@ export function SystemUserTab({
         </div>
       </div>
 
+      {canManage && selectedUserIds.length > 0 && (
+        <div className="flex items-center justify-between gap-4 px-4 py-2.5 rounded-lg border border-[var(--dg-border)] bg-[var(--dg-bg-secondary)]">
+          <span className="text-sm dg-text-secondary">
+            已选择 {selectedUserIds.length} 项 / 共 {filteredUsers.length} 项
+          </span>
+          <div className="flex items-center gap-2">
+            <Button variant="outline" size="sm" className="dg-btn-secondary" onClick={() => setSelectedUserIds([])}>
+              取消选择
+            </Button>
+            <Button variant="outline" size="sm" className="dg-btn-danger dg-btn-sm" onClick={handleBatchDelete}>
+              <Trash2 className="w-4 h-4 mr-2" />
+              批量删除
+            </Button>
+          </div>
+        </div>
+      )}
+
       {/* Users Table */}
       <Card className="bg-[var(--dg-bg-secondary)] border-[var(--dg-border)]">
         <CardContent className="p-0">
@@ -155,6 +192,15 @@ export function SystemUserTab({
             <Table>
               <TableHeader>
                 <TableRow className="border-[var(--dg-border)] hover:bg-transparent">
+                  {canManage && (
+                    <TableHead className="w-10 text-[var(--dg-text-secondary)]">
+                      <Checkbox
+                        checked={allSelected}
+                        onCheckedChange={toggleSelectAll}
+                        className="border-[var(--dg-border)]"
+                      />
+                    </TableHead>
+                  )}
                   <TableHead className="text-[var(--dg-text-secondary)]">用户信息</TableHead>
                   <TableHead className="text-[var(--dg-text-secondary)]">联系方式</TableHead>
                   <TableHead className="text-[var(--dg-text-secondary)]">角色</TableHead>
@@ -167,7 +213,7 @@ export function SystemUserTab({
               <TableBody>
                 {loading ? (
                   <TableRow className="border-[var(--dg-border)]">
-                    <TableCell colSpan={7} className="text-center py-12">
+                    <TableCell colSpan={canManage ? 8 : 7} className="text-center py-12">
                       <div className="flex items-center justify-center">
                         <div className="h-6 w-6 border-2 border-[var(--dg-border)] border-t-[var(--dg-blue)] rounded-full animate-spin" />
                       </div>
@@ -175,13 +221,22 @@ export function SystemUserTab({
                   </TableRow>
                 ) : filteredUsers.length === 0 ? (
                   <TableRow className="border-[var(--dg-border)]">
-                    <TableCell colSpan={7} className="text-center py-12 text-sm text-[var(--dg-text-muted)]">
+                    <TableCell colSpan={canManage ? 8 : 7} className="text-center py-12 text-sm text-[var(--dg-text-muted)]">
                       暂无用户数据
                     </TableCell>
                   </TableRow>
                 ) : (
                   filteredUsers.map((user) => (
                     <TableRow key={user.id} className="border-[var(--dg-border)] hover:bg-[var(--dg-bg-hover)]/50">
+                      {canManage && (
+                        <TableCell>
+                          <Checkbox
+                            checked={selectedUserIds.includes(user.id)}
+                            onCheckedChange={() => toggleSelect(user.id)}
+                            className="border-[var(--dg-border)]"
+                          />
+                        </TableCell>
+                      )}
                       <TableCell>
                         <div className="flex items-center gap-3">
                           <div className="w-8 h-8 rounded-full bg-[var(--dg-blue)] flex items-center justify-center text-white text-sm font-medium">