Fixed backend API, again. Turns out track.getInfo just doesn't feel like serving image data anymore, even though the example response shows it. I love last.fm so much.
Various fixes
Lua dev mode functional
clippy
whitelist -> allowlist
Add SPDX info to all files
Move caching to src/cache/; Finalize API parsing fixes Font and user cache code has been moved to special files, independant from src/config.rs API parsing changes have been properly tested, and last.fm API JSON is now trace-logged for debugging convenience.