Introduced the Game.ts facade — a single entry point that exposes the entire game API as organized domain groups (game.asteroids, game.buildings, game.ships, game.buildMode). This replaces the previous GameOperations approach with a cleaner grouped API. Added useGame as the React hook for accessing it.

Separated asteroid rotation into its own atom to fix an FPS regression where rotation updates were triggering unnecessary re-renders. Cleaned up all the migration planning docs (PLAN.md, RULES.md, STATE-UPDATE.md, etc.) now that the refactor is complete. Updated ARCHITECTURE.md to document the new structure.