Implement the classic Risk board game with full game logic, AI players
with adjustable skill levels (1-5), and Phaser-based rendering.
New files:
- RiskData.js: map data, adjacency graph, continent bonuses, card deck
- RiskLogic.js: pure game engine (reinforce, attack, fortify phases)
- RiskAI.js: heuristic AI with 5 skill tiers and configurable behavior
- RiskGame.js: Phaser scene with combat animations and UI
- tutorial.md: in-game tutorial ("A Field Manual by General Ironside")
- verifyRisk.js: headless fixture and self-play verification script
Integrates with existing game framework via registry, game room dispatch,
and preload scene. Includes board image and updated pawn sprites.
