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.

Reliable user info; Font refactor

Hit a few more endpoints to fix missing images, fallback to default album art just in case.

Refactor the font cache into its own file.

Move the contents of TODO.md to <https://redmine.aleteoryx.me/projects/lfm_embed/issues>.

Clippy

Cleanup

Custom font support complete

Relicense under AGPLv3

Add custom font support.

Add additional services to TODO.md

Remove redundant HTML escaping helpers.

Add helper proposals

Increment version number to 0.1.1

fix typo in plain theme breaking light mode.

Format TODO.md, add watermarking concept.

Add GPL notice to README

Add GPL notice to README

Add todo list

Update README to reflect new site.

add working directory

add systemd service