feat: integrate all 10 skills into homelab-topology

- Added api-security-hardening (helmet, rate limits)
- Added nodejs-backend-patterns (error handling)
- Added observability-monitoring (pino logging)
- Added websocket-engineer (socket.io real-time updates)
- Added docker (Multi-stage build, compose)
- Added vitest (testing configuration and store tests)
- Added data-visualizer (MetricsBar and HostChart)
- Added infrastructure-monitoring/proxmox-admin/network-engineer types
- Fixed UI accessibility and styling
- Cleaned up node_modules tracking

src/components/StaleWarning.tsx

@@ -0,0 +1,41 @@
+import { AlertTriangle, X } from 'lucide-react';
+import { useTopologyStore } from '../store/topologyStore';
+
+export default function StaleWarning() {
+  const { 
+    consecutiveFailures, 
+    lastSuccessfulDiscovery, 
+    staleWarningDismissed,
+    dismissStaleWarning 
+  } = useTopologyStore();
+
+  if (consecutiveFailures < 3 || staleWarningDismissed) {
+    return null;
+  }
+
+  const formatTime = (date: Date | null) => {
+    if (!date) return 'Never';
+    return date.toLocaleString();
+  };
+
+  return (
+    <div className="bg-amber-900/30 border-b border-amber-700/50 px-4 py-2 flex items-center justify-between">
+      <div className="flex items-center gap-3">
+        <AlertTriangle className="w-4 h-4 text-amber-400 flex-shrink-0" />
+        <span className="text-amber-200 text-sm">
+          Data may be stale - Last successful discovery: {formatTime(lastSuccessfulDiscovery)}
+        </span>
+        <span className="text-amber-400/70 text-xs">
+          ({consecutiveFailures} consecutive failures)
+        </span>
+      </div>
+      <button
+        onClick={dismissStaleWarning}
+        className="p-1 hover:bg-amber-800/50 rounded transition-colors"
+        title="Dismiss warning"
+      >
+        <X className="w-4 h-4 text-amber-400" />
+      </button>
+    </div>
+  );
+}