corpus: self-hosted listenbrainz and last.fm frontend

Works as a self-hosted proxy that fetches listening history from either Last.fm or MusicBrainz, adds metadata from MusicBrainz (falling back to Last.fm and Discogs) and caches cover images to an S3 bucket. Everything is stored in DuckDB (each user has their own database) and it's been humming along quite well even for larger profiles (200k scrobbles).

I always worry that these services can disappear without a warning and with them also amazingly extensive listening histories.

I used LLMs quite a lot as I was learning about Purescript and Elm on the fly on the weekends and this is one of the projects I have been thinking about for a long time since other alternatives just seemed a bit lackluster.