Remove unused systemconf.feature_colours from backend * Remove unused routes for `/system/style/{feature}/{attr}`, including the namespace `systemconf` from the schema. This has previously be replaced by a more general mechanism, which is already used by the frontend.

# documentation
**/README*
**/docs
**/*.md

# backend binary
cmd/gemma/gemma

# Dependency directories
.buildbase
**/node_modules

# local dotenv environment variables file
client/.env.local

# Tags tables
**/TAGS