fix(ui): fehlende onError-Handler + i18n in Backends/Domains/Dashboard

- Backends: create + del Mutations bekommen onError; 'Backup'-Tag → t()
- Domains: create + del Mutations bekommen onError
- Dashboard: LicenseChip-Texte ('License OK', 'Trial') in t() überführt;
  useTranslation() direkt in der Komponente verwendet
- en/de: dashboard.licenseOk/licenseTrial/licenseTrialDays ergänzt

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

management-ui/src/i18n/locales/de/common.json

@@ -773,7 +773,10 @@
       "free": "frei",
       "conntrack": "Conntrack",
       "uptime": "Uptime"
-    }
+    },
+    "licenseOk": "Lizenz OK",
+    "licenseTrial": "Trial",
+    "licenseTrialDays": "Trial · {{days}}d"
   },
   "ntp": {
     "title": "Zeitserver (Chrony)",

management-ui/src/i18n/locales/en/common.json

@@ -773,7 +773,10 @@
       "free": "free",
       "conntrack": "Conntrack",
       "uptime": "Uptime"
-    }
+    },
+    "licenseOk": "License OK",
+    "licenseTrial": "Trial",
+    "licenseTrialDays": "Trial · {{days}}d"
   },
   "ntp": {
     "title": "Time server (Chrony)",

management-ui/src/pages/Backends/index.tsx

@@ -216,11 +216,13 @@ export default function BackendsPage() {
       void qc.invalidateQueries({ queryKey: ['backends'] })
       void qc.invalidateQueries({ queryKey: ['domains'] })
     },
+    onError: (e: Error) => message.error(e.message),
   })
 
   const del = useMutation({
     mutationFn: async (id: number) => { await apiClient.delete(`/backends/${id}`) },
     onSuccess: () => { void qc.invalidateQueries({ queryKey: ['backends'] }) },
+    onError: (e: Error) => message.error(e.message),
   })
   const quickToggle = useMutation({
     mutationFn: async ({ id, row, checked }: { id: number; row: Backend; checked: boolean }) => {
@@ -453,7 +455,7 @@ function ServerPanel({ backendID }: { backendID: number }) {
     },
     { title: t('backends.server.weight'), dataIndex: 'weight', width: 80 },
     { title: t('backends.server.backup'), dataIndex: 'backup',
-      render: (v: boolean) => v ? <Tag color="purple">Backup</Tag> : '—', width: 100 },
+      render: (v: boolean) => v ? <Tag color="purple">{t('backends.server.backup')}</Tag> : '—', width: 100 },
     {
       title: t('backends.active'), dataIndex: 'active', width: 80,
       render: (v: boolean, row: BackendServer) => (

management-ui/src/pages/Dashboard/index.tsx

@@ -713,6 +713,7 @@ function LicenseChip({ data }: { data: {
   expires_at?: string
   license_key?: string
 }}) {
+  const { t } = useTranslation()
   const exp = data.valid_until ?? data.expires_at
   const days = exp ? Math.ceil((new Date(exp).getTime() - Date.now()) / 86_400_000) : null
   const isTrial = data.type === 'trial' || (!data.license_key && data.status === 'active')
@@ -720,12 +721,15 @@ function LicenseChip({ data }: { data: {
     return <Tag color="red">{data.status}</Tag>
   }
   if (isTrial) {
-    if (days != null && days <= 7) return <Tag color="red">Trial · {days}d</Tag>
-    if (days != null && days <= 14) return <Tag color="orange">Trial · {days}d</Tag>
-    return <Tag color="blue">{days != null ? `Trial · ${days}d` : 'Trial'}</Tag>
+    const trialLabel = days != null
+      ? t('dashboard.licenseTrialDays', { days })
+      : t('dashboard.licenseTrial')
+    if (days != null && days <= 7) return <Tag color="red">{trialLabel}</Tag>
+    if (days != null && days <= 14) return <Tag color="orange">{trialLabel}</Tag>
+    return <Tag color="blue">{trialLabel}</Tag>
   }
   if (data.status === 'active') {
-    return <Tag color="green">License OK</Tag>
+    return <Tag color="green">{t('dashboard.licenseOk')}</Tag>
   }
   return null
 }

management-ui/src/pages/Domains/index.tsx

@@ -167,6 +167,7 @@ export default function DomainsPage() {
       form.resetFields()
       void qc.invalidateQueries({ queryKey: ['domains'] })
     },
+    onError: (e: Error) => message.error(e.message),
   })
 
   const del = useMutation({
@@ -176,6 +177,7 @@ export default function DomainsPage() {
     onSuccess: () => {
       void qc.invalidateQueries({ queryKey: ['domains'] })
     },
+    onError: (e: Error) => message.error(e.message),
   })
   const quickToggle = useMutation({
     mutationFn: async ({ id, row, checked }: { id: number; row: Domain; checked: boolean }) => {