Move all the code for defining tag categories from the config file to TagCategory. It didn't belong in the config because it's not possible to add new tag categories purely in the config without editing other things like the CSS. Also change it so that tag colors are hardcoded in the CSS instead of generated using ERB. Generating the CSS in ERB meant that the Docker build had to recompile the CSS on every commit, even when it didn't change, because it relied on Ruby code outside the CSS that we couldn't guarantee didn't change.
Config
This directory contains configuration files for Danbooru.
To configure your Danbooru instance, copy danbooru_default_config.rb to danbooru_local_config.rb and edit it. See danbooru_default_config.rb for details.
The only file here that end users need to be concerned about is danbooru_default_config.rb. The rest of the files here are internal Rails-related configuration files that end users shouldn't need to edit.