I have this Next JS 14 app which is basically a shopping cart. I build the app with output: 'export' in the next.config.mjs file. How can I add this to an existing website (PHP generated) so it doesn’t mess up with it. I tried to include (or even echo the content of) the index.html which is generated by Next in the PHP website but as soon as the JS files are loaded, they take over the entire screen. (The existing PHP generated website has a sidebar and a navbar and I want the Next JS generated code to appear as the content).