v0.2.1

Summary

• Refactor architecture with a new GameEngine wrapper above GameState and move app flow/mode handling into engine.
• Split GameState responsibilities into focused subsystems (AI, combat, production, flow, effects, config loaders, time system).
• Extract unit/building rendering/runtime helpers and add handoff documentation with runtime/dependency diagrams.

Test plan

• Build with Processing CLI via build.ps1
• Verify no linter errors on touched files
• Manual gameplay smoke test (menu/pause, move/attack/A-move, build/train/cancel, win/lose overlay)