New game: Target Chess

Deal 4 cards at start, mixed colours. When all pieces are captured, you get a bonus. Drops? Double for your own colour? Deal 6 keep 4?

When you reveal your target, place your sacrificed pieces on their matching cards, then add one of your lost pieces to each card. You can then drop pieces from cards later in the game. If you haven't lost enough pieces when you reveal your target cards, you can't add any later. You may wait to reveal.

No files, tests, or entry points are named. Start by reviewing the existing game implementations in chess-kit and clarify the proposed Target Chess rules; done means the deal, target reveal, piece placement, later drops, and completion bonus behavior are specified and implemented.

Written by the indexing model from the issue text.