feat(ui): Quick-Toggles, Config-Preview, Dashboard-Alerts, Domain-Detail-Health

Quick-Toggle-Switches (kein Modal nötig) für: Backends, Backend-Server,
DNS-Zonen, DNS-Records, Domains (active), Firewall-Rules, NAT-Rules,
Forward-Proxy ACLs, Routing-Rules.

Dashboard: Alert-Banner für komplett ausgefallene Backends (HAProxy-Stats)
und Domains im Maintenance-Mode.

Domain-Detail: HAProxy-Live-Health-Badge (15s Polling), TLS-Cert
ausstellen/erneuern direkt aus dem Detail, Routing-Rules-Panel inline.

Config-Preview (Settings): alle 4 Generatoren (haproxy, nftables, squid,
unbound) rendern via RenderToString ohne Disk-Write — GET /system/config-preview.

ActionButtons: Viewer-Rolle blendet Delete aus (RBAC-Ergänzung).

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

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

@@ -63,7 +63,7 @@ function useAuditLive(keep = 15) {
 
 // ── Wire shapes ───────────────────────────────────────────────
 
-interface Domain   { id: number; active: boolean; primary_backend_id?: number | null }
+interface Domain   { id: number; name: string; active: boolean; primary_backend_id?: number | null; maintenance_mode: boolean }
 interface Backend  { id: number; active: boolean; name: string }
 interface Iface    { id: number; active: boolean; name: string; type: string }
 interface FwRule   { id: number; enabled: boolean; action: string }
@@ -251,6 +251,33 @@ export default function DashboardPage() {
                                                         && Date.now() / 1000 - s.last_handshake_unix < 180).length
 
   const now = Date.now()
+  const maintenanceDomains = (domains.data ?? []).filter(d => d.maintenance_mode)
+
+  // Backends die komplett DOWN sind (mind. 1 Server mit echtem Check,
+  // aber kein einziger UP) — liefert friendly Backend-Namen.
+  const downBackends = (() => {
+    const stats = haproxyBackends.data ?? []
+    const bklist = backends.data ?? []
+    if (!stats.length || !bklist.length) return []
+    // gruppiere Stat-Zeilen nach HAProxy-Backend-Name (eg_backend_<id>)
+    const byBackend = new Map<string, typeof stats>()
+    for (const s of stats) {
+      const arr = byBackend.get(s.backend) ?? []; arr.push(s)
+      byBackend.set(s.backend, arr)
+    }
+    const down: string[] = []
+    for (const [haName, servers] of byBackend) {
+      const hasRealCheck = servers.some(s => s.status !== 'no check')
+      if (hasRealCheck && !servers.some(s => s.status === 'UP')) {
+        const m = /^eg_backend_(\d+)$/.exec(haName)
+        const id = m ? Number(m[1]) : null
+        const b = id != null ? bklist.find(x => x.id === id) : null
+        down.push(b?.name ?? haName)
+      }
+    }
+    return down
+  })()
+
   const certsSoon = (tlsCerts.data ?? []).filter(c => {
     if (!c.not_after) return false
     const exp = new Date(c.not_after).getTime()
@@ -303,6 +330,34 @@ export default function DashboardPage() {
         />
       )}
 
+      {downBackends.length > 0 && (
+        <Alert
+          type="error"
+          showIcon
+          className="mb-12"
+          message={t('dashboard.downBackendsAlert', { count: downBackends.length })}
+          description={
+            <Space wrap size={4}>
+              {downBackends.map(name => <Link key={name} to="/backends">{name}</Link>)}
+            </Space>
+          }
+        />
+      )}
+
+      {maintenanceDomains.length > 0 && (
+        <Alert
+          type="warning"
+          showIcon
+          className="mb-12"
+          message={t('dashboard.maintenanceAlert', { count: maintenanceDomains.length })}
+          description={
+            <Space wrap size={4}>
+              {maintenanceDomains.map(d => <Link key={d.id} to={`/domains/${d.id}`}>{d.name}</Link>)}
+            </Space>
+          }
+        />
+      )}
+
       {/* ── KPI tiles (compact strip) ──────────────────── */}
       <Row gutter={[12, 12]} className="mb-12">
         <KPI icon={<GlobalOutlined />}      label={t('dashboard.kpi.domains')}  value={activeDomains}  total={(domains.data ?? []).length} />