feat: umfangreiches UI+API-Polish (v1.1.36–1.1.42)

Backend:
- Audit-Log: Search-Endpoint mit ILIKE-Filter (actor/action/subject/date)
- NTP: /ntp/status via chronyc tracking (Stratum, Offset, Quelle)
- System: /service-restart mit Allowlist (haproxy/squid/unbound/chrony/scheduler)
- Domain-Response-Headers + Rate-Limit (Migration 0024)
- Join-Tokens (Migration 0025), Cluster-mTLS, Aggregator-Fan-Out
- apt-Service für Update-Banner (apt-get update + Versionsprüfung)
- Backup-Retry mit exponential backoff (retry_apt 3×)
- publish.sh fail-fast + cleanup-old.sh (max 10 Versionen)

Frontend:
- Audit-Log-Page (/audit) mit Filter + Pagination
- ErrorBoundary an React-Root + Vite build-target festgenagelt (iOS 15+)
- Storage-Schema-Stamp: auto-wipe bei Versions-Mismatch (blank-page-Fix)
- EmptyState-Komponente überall ausgerollt
- SSL: Aggregate-Karte (total/expiring/expired/errors)
- Backups: Aggregate-Karte (letzter Backup/Größe/Fehlschläge 24h) + Backup-Now
- NTP: Sync-Status-Karte (chronyc tracking live)
- Domains: Backend-UP/DOWN-Chip aus HAProxy-Stats
- Backends: HAProxy-Status-Spalte (UP/DEGRADED/DOWN)
- Settings: Service-Neustart-Karte (haproxy/squid/unbound/chrony/scheduler)
- Settings: Upgrade-Status-Card, Wartungsmodus, Auto-Update, Retention
- Dashboard: Recent-Alerts, Cluster-Health, License-Chip, Onboarding-Hint
- System-Regeln im Firewall als eigener Tab

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

management-ui/src/pages/Firewall/NATRules.tsx

@@ -3,7 +3,10 @@ import { Button, Form, Input, InputNumber, Modal, Popconfirm, Select, Space, Swi
 import type { ColumnsType } from 'antd/es/table'
 import { useMutation, useQuery, useQueryClient } from '@tanstack/react-query'
 import { useTranslation } from 'react-i18next'
+import { BranchesOutlined } from '@ant-design/icons'
+
 import DataTable from '../../components/DataTable'
+import EmptyState from '../../components/EmptyState'
 
 import apiClient, { isEnvelope } from '../../api/client'
 import type { FwZone, NATRule } from './types'
@@ -132,15 +135,30 @@ export default function NATRulesTab() {
     },
   ]
 
+  const openCreate = () => {
+    setCreating(true); form.resetFields()
+    form.setFieldsValue({ priority: 100, enabled: true, kind: 'dnat' })
+  }
+
   return (
     <>
-      <Button type="primary" className="mb-16" onClick={() => {
-        setCreating(true); form.resetFields()
-        form.setFieldsValue({ priority: 100, enabled: true, kind: 'dnat' })
-      }}>
+      <Button type="primary" className="mb-16" onClick={openCreate}>
         {t('fw.nat.add')}
       </Button>
-      <DataTable rowKey="id" loading={isLoading} dataSource={data ?? []} columns={columns}  />
+      <DataTable
+        rowKey="id"
+        loading={isLoading}
+        dataSource={data ?? []}
+        columns={columns}
+        emptyContent={
+          <EmptyState
+            icon={<BranchesOutlined />}
+            title={t('fw.nat.emptyTitle')}
+            description={t('fw.nat.emptyDesc')}
+            action={<Button type="primary" onClick={openCreate}>{t('fw.nat.add')}</Button>}
+          />
+        }
+      />
       <Modal
         title={editing ? t('fw.nat.edit') : t('fw.nat.add')}
         open={editing !== null || creating}