Add an optional "single word per turn" rule: only the main word along the
play direction is validated and scored; perpendicular cross-words are ignored
— not formed, validated, scored, or used to constrain move generation. The
zero PlayOptions stays standard Scrabble, so existing callers are unchanged.
- PlayOptions{IgnoreCrossWords} threaded through new EvaluateOpts,
Solver.{ScorePlay,ValidatePlay,GenerateMoves}Opts and the DAWG generator
(relaxed cross-sets via fullSet, main-word-only scoring).
- connected() tests perpendicular adjacency directly instead of via
Move.Cross, so an all-new main word touching the board only sideways still
connects when cross-words are suppressed (behaviour-preserving for standard
play).
- Tests: focused corner-case suite (solver_opts_test.go) and a single-word
GCG fixture; the 17 real-game GCG fixtures stay green as the standard-rules
regression guard.
Ilia Denisov