New Game: Chess Golf

Same movement mechanic as #20 Neighbour Chess, but as a puzzle race game. Are Neighbour Chess and Chess Golf too similar to include both?

* [x] Add rules.
* [x] Add some examples.
* [x] Add pieces back before dealing.
* [x] Dealer chooses par 2, 3, or maybe 4 by dealing more cards.
* [x] If a colour has no legal moves, then you may make a king move with any piece of that colour.
* [ ] Generate interesting problems to solve.
* [ ] Reduce memory usage in `GolfGraph`, or dump state to a db.
* [ ] Simulate a bunch of games, and give quartile scores as targets for solitaire play.
* [ ] Explain why it's called golf sooner in rules. Explain why target can move? Jousting theme with squires?
* [ ] Clarify which diagram you're talking about in rules.
* [ ] Special move sounds like expansion? How about, "No Partners" or "When You Have No Partners"?
* [ ] Repeat that you may move more than one piece and pieces other than the targets.
* [ ] Simplify the description of difficulty level, and just give it as an option after everyone has had a few turns of practice. Also clarify that only 2 or 3 cards are recommended.
* [ ] Add difficulty level that requires n different move types? Too hard to keep track of?
* [ ] Clarify that layout gaps wrap.

No files or tests are named; start by locating the Chess Golf rules and the `GolfGraph` implementation, then review the unchecked items and existing examples. Done means the remaining gameplay, memory, simulation, and rules-clarity tasks are resolved and the game remains understandable and playable.

Written by the indexing model from the issue text.