nostr:npub1hee433872q2gen90cqh2ypwcq9z7y5ugn23etrd2l2rrwpruss8qwmrsv6 file upload would be dead simple especially since you already have an endpoint to upload to nostr:npub1nxy4qpqnld6kmpphjykvx2lqwvxmuxluddwjamm4nc29ds3elyzsm5avr7. Just need to add an upload form somewhere to let the user enter some metadata. 

It would help if you add a README with how to run the app in development.