* add yiq calculator util
* fix: convert 3 chars hex to 6 chars hex
* fix: clarify util name
* feat: add text color variables not depending on the dark/light mode
* refactor: change getContrast to isDark with for a more direct approach
* fix: adjust snippet description
* chore: change `var` to `let`
Co-authored-by: David Wheatley <david@davwheat.dev>