feat(App): replace PageLoader with LazyLoader for improved loading experience

src/app/App.tsx

@@ -13,6 +13,7 @@ import MediaManager             from './components/MediaManager';
 import logoSvg from '../imports/logo.svg';
 import { useSettings } from './settings';
 import { WsProvider } from './ws';
+import { LazyLoader } from './components/ui/lazy-loader';
 
 // Three.js lives only in RealityOverridePage — keep lazy so it doesn't load on startup.
 // CodeMirror/syntax-highlighter/ReactMarkdown live in MediaViewerEditor — lazy-loaded
@@ -47,13 +48,6 @@ type AppId =
   | 'reality-override'
   | 'reality-override-admin';
 
-function PageLoader() {
-  return (
-    <div className="flex items-center justify-center h-full text-neutral-400">
-      <Loader2 className="w-6 h-6 animate-spin" />
-    </div>
-  );
-}
 
 export default function App() {
   const [currentPage, setCurrentPage] = useState<Page>('status');
@@ -314,7 +308,7 @@ function AppPage({ title, onBack }: { title: string; onBack: () => void }) {
       </header>
 
       <main className="flex-1 overflow-y-auto">
-        <Suspense fallback={<PageLoader />}>
+        <Suspense fallback={<LazyLoader />}>
           {pages[currentPage]}
         </Suspense>
       </main>

src/app/components/ui/lazy-loader.tsx

@@ -0,0 +1,38 @@
+import { useEffect, useState } from 'react';
+import { Loader2 } from 'lucide-react';
+
+export function LazyLoader() {
+  const [pct, setPct] = useState(0);
+
+  useEffect(() => {
+    const steps: [number, number][] = [
+      [80,   30],
+      [400,  60],
+      [1200, 80],
+      [2500, 92],
+    ];
+    const timers = steps.map(([delay, val]) => setTimeout(() => setPct(val), delay));
+    return () => timers.forEach(clearTimeout);
+  }, []);
+
+  const duration =
+    pct <=  30 ? '150ms' :
+    pct <=  60 ? '500ms' :
+    pct <=  80 ? '1000ms' : '1500ms';
+
+  return (
+    <div className="fixed inset-0 bg-neutral-950 z-40 flex flex-col items-center justify-center">
+      <div className="absolute top-0 left-0 right-0 h-[2px] bg-neutral-800 overflow-hidden">
+        <div
+          className="h-full bg-blue-500 transition-[width] ease-out"
+          style={{ width: `${pct}%`, transitionDuration: duration }}
+        />
+      </div>
+
+      <div className="flex flex-col items-center gap-3 text-neutral-600">
+        <Loader2 className="w-5 h-5 animate-spin" />
+        <span className="text-xs tracking-wide">Loading…</span>
+      </div>
+    </div>
+  );
+}