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/DNS/index.tsx

@@ -7,6 +7,7 @@ import { useTranslation } from 'react-i18next'
 
 import apiClient, { isEnvelope } from '../../api/client'
 import DataTable from '../../components/DataTable'
+import EmptyState from '../../components/EmptyState'
 import PageHeader from '../../components/PageHeader'
 import ActionButtons from '../../components/ActionButtons'
 import StatusDot from '../../components/StatusDot'
@@ -152,6 +153,11 @@ function ZonesTab() {
     },
   ]
 
+  const openZoneCreate = () => {
+    setCreating(true); form.resetFields()
+    form.setFieldsValue({ zone_type: 'local', active: true } as Zone)
+  }
+
   return (
     <>
       <DataTable
@@ -160,13 +166,22 @@ function ZonesTab() {
         dataSource={data ?? []}
         columns={cols}
         extraActions={
-          <Button type="primary" icon={<PlusOutlined />} onClick={() => {
-            setCreating(true); form.resetFields()
-            form.setFieldsValue({ zone_type: 'local', active: true } as Zone)
-          }}>
+          <Button type="primary" icon={<PlusOutlined />} onClick={openZoneCreate}>
             {t('dns.zone.add')}
           </Button>
         }
+        emptyContent={
+          <EmptyState
+            icon={<GlobalOutlined />}
+            title={t('dns.zone.emptyTitle')}
+            description={t('dns.zone.emptyDesc')}
+            action={
+              <Button type="primary" icon={<PlusOutlined />} onClick={openZoneCreate}>
+                {t('dns.zone.add')}
+              </Button>
+            }
+          />
+        }
       />
 
       <Modal
@@ -273,6 +288,11 @@ function RecordsDrawer({ zone, onClose }: RecordsDrawerProps) {
     },
   ]
 
+  const openRecordCreate = () => {
+    setCreating(true); form.resetFields()
+    form.setFieldsValue({ record_type: 'A', ttl: 300, active: true } as DNSRecord)
+  }
+
   return (
     <Drawer
       open={open}
@@ -292,13 +312,22 @@ function RecordsDrawer({ zone, onClose }: RecordsDrawerProps) {
         dataSource={data ?? []}
         columns={cols}
         extraActions={
-          <Button type="primary" icon={<PlusOutlined />} onClick={() => {
-            setCreating(true); form.resetFields()
-            form.setFieldsValue({ record_type: 'A', ttl: 300, active: true } as DNSRecord)
-          }}>
+          <Button type="primary" icon={<PlusOutlined />} onClick={openRecordCreate}>
             {t('dns.record.add')}
           </Button>
         }
+        emptyContent={
+          <EmptyState
+            icon={<NodeIndexOutlined />}
+            title={t('dns.record.emptyTitle')}
+            description={t('dns.record.emptyDesc')}
+            action={
+              <Button type="primary" icon={<PlusOutlined />} onClick={openRecordCreate}>
+                {t('dns.record.add')}
+              </Button>
+            }
+          />
+        }
       />
 
       <Modal