feat(ui): replace skeleton loaders with honest loading states

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

frontend/src/routes/_authenticated.tsx

@@ -12,7 +12,7 @@ import { EventStreamProvider } from '@/contexts/EventStreamContext'
 import type { FleetDevice } from '@/lib/api'
 import { AppLayout } from '@/components/layout/AppLayout'
 import { PageTransition } from '@/components/layout/PageTransition'
-import { Skeleton } from '@/components/ui/skeleton'
+import { LoadingText } from '@/components/ui/skeleton'
 import { ErrorBoundary } from '@/components/ui/error-boundary'
 
 export const Route = createFileRoute('/_authenticated')({
@@ -164,11 +164,7 @@ function AuthenticatedLayout() {
   if (isLoading) {
     return (
       <div className="flex items-center justify-center min-h-screen bg-background">
-        <div className="space-y-4 w-64">
-          <Skeleton className="h-8 w-48 mx-auto" />
-          <Skeleton className="h-4 w-full" />
-          <Skeleton className="h-4 w-3/4" />
-        </div>
+        <LoadingText />
       </div>
     )
   }

frontend/src/routes/_authenticated/tenants/$tenantId/devices/$deviceId.tsx

@@ -800,7 +800,7 @@ function DeviceAlertsSection({
   const resolvedAlerts = alerts.filter((a) => a.status === 'resolved').slice(0, 5)
 
   if (isLoading) {
-    return <TableSkeleton rows={3} />
+    return <TableSkeleton />
   }
 
   return (

frontend/src/routes/_authenticated/tenants/$tenantId/index.tsx

@@ -23,7 +23,7 @@ function TenantDetailPage() {
   })
 
   if (isLoading) {
-    return <CardGridSkeleton cards={3} />
+    return <CardGridSkeleton />
   }
 
   if (!tenant) {

frontend/src/routes/_authenticated/tenants/$tenantId/sites/$siteId.tsx

@@ -26,9 +26,8 @@ function SiteDetailPage() {
 
   if (isLoading) {
     return (
-      <div className="animate-pulse space-y-4">
-        <div className="h-6 w-48 bg-elevated rounded" />
-        <div className="h-4 w-64 bg-elevated rounded" />
+      <div className="py-8 text-center">
+        <span className="text-[9px] text-text-muted">Loading&hellip;</span>
       </div>
     )
   }