I know this is kind of the contrarian opinion and I'm not trying to be "that guy", but if you want a web app that works in 30 years you would probably be best o

I know this is kind of the contrarian opinion and I'm not trying to be "that guy", but if you want a web app that works in 30 years you would probably be best off building a server-side rendered application. You need a server, HTTP, HTML, and CSS for any web application, but you don't always need a lot of client side javascript. The fewer things you have in your stack, the fewer things can change under your feet.