It is, in fact, all original work. Much of it has never been off the hard drive it was generated on (the stuff by local models), and when Riffusion got bought out they deleted all the stuff their users had generated so my local copies of those are the only ones left. The metadata is in sidecar .json files, except for the Udio tracks which were in .txt files that first needed to be converted to .json. All very ad-hoc stuff to begin with.

Also, it looks like Dropped Needle is aiming to make the music available for streaming through things like Jellyfin. That's not what I wanted, I wanted to make a web site specifically so that I could control the layout and contents for when I share it with friends (many of whom are not technically savvy and so only know how to click on a web URL).

This really wasn't a "just use pre-existing application X" situation. Even if there had been one that could handle all of that, configuring it would have taken just as much work as explaining to the coding AI what I wanted.