feat: add Civilization II-lite game engine and UI
Implement a complete turn-based strategy game with:
- Deterministic headless engine: cities, units, combat, research, governments
- Seeded world generation with noise-based terrain, continents, quality scoring
- Isometric map renderer with procedural fallbacks and optional sprite sheets
- AI rivals with strategy phases, diplomacy, trade routes, and unit control
- Full UI: setup, city screen, tech tree, diplomacy, spaceship tracker, victory
- 80 techs, 51 units, 26 buildings, 11 terrains, 6 governments, 5 difficulties
- Comprehensive headless verification suite (rules integrity, worldgen, combat, AI self-play)
Brian Fertig
67a7ac857e