Five Dice Scorecard Showdown

Builds a complete, playable single-file dice-scorecard game (roll 5 dice, fill a 13-category scorecard) with the upper bonus and the full Joker Rule for bonus five-of-a-kind rolls implemented per the official priority order. Found and fixed a real bug via unit testing against the printed rule text — a zeroed scorecard box was wrongly treated as bonus-eligible. 50 unit tests plus 120 automated random games (1,560 turns), 0 errors. (AI-assisted, hand-verified.)