add Galactic Admin mode banner to Fleet Health page

Shows a prominent purple banner when galacticAdminMode is active,
clearly indicating that data is aggregated across all tenants.

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

src/Web/autopilot-monitor-web/app/fleet-health/page.tsx

@@ -362,6 +362,15 @@ export default function FleetHealthPage() {
   return (
     <ProtectedRoute>
       <div className="min-h-screen bg-gray-50">
+        {galacticAdminMode && (
+          <div className="bg-purple-700 text-white text-sm px-4 py-2 flex items-center justify-center space-x-2">
+            <svg className="w-4 h-4 flex-shrink-0" fill="none" viewBox="0 0 24 24" stroke="currentColor">
+              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M3.055 11H5a2 2 0 012 2v1a2 2 0 002 2 2 2 0 012 2v2.945M8 3.935V5.5A2.5 2.5 0 0010.5 8h.5a2 2 0 012 2 2 2 0 104 0 2 2 0 012-2h1.064M15 20.488V18a2 2 0 012-2h3.064M21 12a9 9 0 11-18 0 9 9 0 0118 0z" />
+            </svg>
+            <span className="font-medium">Galactic Admin View</span>
+            <span className="text-purple-300">&mdash; aggregating data across all tenants</span>
+          </div>
+        )}
         <header className="bg-white shadow">
           <div className="max-w-7xl mx-auto py-6 px-4 sm:px-6 lg:px-8">
             <div className="flex items-center justify-between">
@@ -387,7 +396,7 @@ export default function FleetHealthPage() {
                     />
                   </svg>
                   <h1 className="text-3xl font-bold text-gray-900">
-                    Feet Health
+                    Fleet Health
                   </h1>
                 </div>
               </div>