fix(i18n): hardkodierte Strings in DNS/RoutingRules/Settings/Backends bereinigen

- DNS Settings: Loopback/allIPv4/allIPv6 Interface-Labels in t() überführt
- RoutingRules: UP/DOWN-Tags + fehlende onError-Handler in create/update
- Settings: t-Variable-Shadowing in top_tables-Map behoben (t → tbl)
- Backends: 'Live'-Spaltenheader → t('backends.server.live')
- common.up/down + dns.settings.allIPv4/allIPv6/loopback in en+de ergänzt

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

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

@@ -309,7 +309,7 @@ function ServerPanel({ backendID, haproxyStats }: { backendID: number; haproxySt
       ),
     },
     {
-      title: 'Live', key: 'live', width: 160,
+      title: t('backends.server.live'), key: 'live', width: 160,
       render: (_, r) => {
         const stat = haproxyStats.find(
           s => s.backend === `eg_backend_${backendID}` && s.server === r.name