[Update] Combine in one window. Rename Main/Config Window to Main/Config Page accordingly.

For now, I put Config Page to below the main page temporary. Open Config Button does not work.

index.html

@@ -9,6 +9,6 @@
 
     <body>
         <div id="root"></div>
-        <script type="module" src="./src-ui/windows/main_window/index.jsx"></script>
+        <script type="module" src="./src-ui/app/index.jsx"></script>
     </body>
 </html>