design: upgrade global design of the app

src/main.tsx

@@ -1,6 +1,7 @@
 import React from "react";
 import ReactDOM from "react-dom/client";
 import App from "./App";
+import ImageViewerWindow from "./components/ImageViewerWindow";
 
 // Block all document-level scrolling
 document.addEventListener("wheel", (e) => {
@@ -17,8 +18,10 @@ document.addEventListener("scroll", () => {
   window.scrollTo(0, 0);
 }, { passive: true });
 
+const isViewer = new URLSearchParams(window.location.search).get("viewer") === "1";
+
 ReactDOM.createRoot(document.getElementById("root") as HTMLElement).render(
   <React.StrictMode>
-    <App />
+    {isViewer ? <ImageViewerWindow /> : <App />}
   </React.StrictMode>,
 );