feat(ux): Hostname in Sidebar + CPU-Anzahl neben Load Average

- Sidebar: Hostname unter der Versionsnummer (aus /system/health);
  10px, gedimmt — beim Verwalten mehrerer Boxen sofort erkennbar
- /system/resources: neues Feld num_cpus (via runtime.NumCPU)
- Dashboard Resources-Card: Load-Average-Label zeigt "(N CPU)" —
  1.80 auf 1 CPU ist saturiert, auf 4 CPUs ist es harmlos

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

management-ui/src/components/Layout/Sidebar.tsx

@@ -112,13 +112,16 @@ export default function Sidebar({ isOpen, onClose }: SidebarProps) {
     queryKey: ['system', 'health'],
     queryFn: async () => {
       const r = await apiClient.get('/system/health')
-      return isEnvelope(r.data) ? (r.data.data as { version?: string }) : { version: '' }
+      return isEnvelope(r.data)
+        ? (r.data.data as { version?: string; hostname?: string })
+        : { version: '' }
     },
     refetchInterval: 60_000,
     refetchOnWindowFocus: true,
     staleTime: 30_000,
   })
-  const version = health?.version || '…'
+  const version  = health?.version  || '…'
+  const hostname = health?.hostname || null
 
   return (
     <nav className={`sidebar${isOpen ? ' open' : ''}`}>
@@ -162,7 +165,14 @@ export default function Sidebar({ isOpen, onClose }: SidebarProps) {
         </div>
       ))}
 
-      <div className="sidebar-version">v{version}</div>
+      <div className="sidebar-version">
+        {hostname && (
+          <div style={{ fontSize: 10, opacity: 0.6, marginBottom: 2, overflow: 'hidden', textOverflow: 'ellipsis', whiteSpace: 'nowrap' }}>
+            {hostname}
+          </div>
+        )}
+        v{version}
+      </div>
     </nav>
   )
 }

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

@@ -89,6 +89,7 @@ interface ServiceStatus {
 }
 interface Resources {
   load_avg_1: number; load_avg_5: number; load_avg_15: number
+  num_cpus?: number
   mem_total_kb: number; mem_avail_kb: number; mem_used_pct: number
   disk_total_gb: number; disk_free_gb: number; disk_used_pct: number
   conntrack_count: number; conntrack_max: number
@@ -664,7 +665,10 @@ function ResourcesCard({ r }: { r?: Resources | null }) {
       <Card size="small">
         <Row gutter={[16, 8]}>
           <Col xs={12} sm={6} md={4}>
-            <Text type="secondary" style={{ fontSize: 11, textTransform: 'uppercase' }}>{t('dashboard.resCard.load')}</Text>
+            <Text type="secondary" style={{ fontSize: 11, textTransform: 'uppercase' }}>
+              {t('dashboard.resCard.load')}
+              {r.num_cpus != null && <span style={{ fontWeight: 400, opacity: 0.7 }}> ({r.num_cpus} CPU)</span>}
+            </Text>
             <div style={{ fontSize: 18, fontWeight: 600 }}>
               {r.load_avg_1.toFixed(2)} / {r.load_avg_5.toFixed(2)} / {r.load_avg_15.toFixed(2)}
             </div>