Fix hitbox misalignment where Phaser's Container displayOrigin already
centers bounds, causing manual Rectangle offsets to double-shift.
feat: add Rummikub game with AI, immutable engine, and solver
- Implement full Rummikub gameplay: drag & drop, sets/runs, jokers,
table manipulation, opening meld rule, and scoring
- Add immutable game engine (RummikubLogic) following existing patterns
- Add rules solver (RummikubSolver) for set validation and AI planning
- Implement 5-level heuristic AI (RummikubAI) with configurable delay
- Register game in registry and routing, include tutorial markdown
- Add headless verification script (fixture tests + AI self-play)
