airkjw
62cbb4b16a
Add objectives, stage config, and GameEngine session core
Sealed Objective types (clearGems/reachScore/clearLines) with JSON
round-trip; StageConfig with preset cells and star thresholds;
GameEngine orchestrating placement -> clear -> scoring -> objectives
with stuck detection, one-shot rescue (continue / +5 moves), and
deterministic per-attempt RNG. 100-game headless stress test and
pure-Dart architecture guard. 76 tests green.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>