feat(setup): improve color contrast

[trueNAHO]

• feat(setup): improve c.colors.completion contrast
  • Using striking colors for matched items enhances perception with minimal cognitive strain. Unfortunately, c.colors.completion.item.selected.match.fg is no longer slightly brighter than c.colors.completion.match.fg because they now share the same color. This results from the strong contrast between peach and maroon.
• feat(setup): increase c.colors.hints contrast
  • Contrast based on c.colors.hints.bg and c.colors.hints.match.fg.