perf(library): persistent SPA shell, in-memory folder tree caching, and zero-flicker LRU thumbnail caching

docker/frontend/src/main.tsx

@@ -37,7 +37,6 @@ function pick(route: string) {
   );
 }
 
-// Intercept internal link clicks for instant SPA transitions without full page reload
 function Shell() {
   const [route, setRoute] = useState(() => window.location.pathname + window.location.search);
 
@@ -64,7 +63,31 @@ function Shell() {
     };
   }, []);
 
-  return pick(route);
+  const isApp = route.startsWith('/app');
+  const isLibrary = route.startsWith('/library');
+  const isOther = !isApp && !isLibrary;
+
+  return (
+    <>
+      <div style={{ display: isApp ? 'block' : 'none', height: '100%' }}>
+        <Workspace />
+      </div>
+      <div style={{ display: isLibrary ? 'block' : 'none', height: '100%' }}>
+        <Library />
+      </div>
+      {isOther ? (
+        route.startsWith('/admin') ? (
+          <Admin />
+        ) : route.startsWith('/photos') ? (
+          <PhotosPage />
+        ) : route.startsWith('/profile') ? (
+          <ProfilePage />
+        ) : (
+          <Landing />
+        )
+      ) : null}
+    </>
+  );
 }
 
 const root = document.getElementById('root');