Accent presets and fresh card backs

Improved

• The Settings accent color now paints the whole app, and four hand-picked presets let you set the tone
• The board legend only appears when a tile needs explaining, and circuit boards get a lap-chip entry so you know which lap you are on
• The pegging count now sits centered between the rails, and cards fade when a peg is buried behind them so the pile stays readable
• The challenge pre-flight card now spells out what each side brings before you start
• Settings dropped the old card-back and felt-color rows that no longer did anything