Core game state models:
- Zone: Card collection with deck operations (draw, shuffle, peek, etc.)
- PlayerState: All player zones, score, and per-turn action flags
- GameState: Complete game state with card registry, turn tracking, win conditions
Test fixtures (conftest.py):
- Sample card definitions: Pokemon (Pikachu, Raichu, Charizard, EX, V, VMAX)
- Trainer cards: Item (Potion), Supporter (Professor Oak), Stadium, Tool
- Energy cards: Basic and special energy
- Pre-configured game states: empty, mid-game, near-win scenarios
- Factory fixtures for CardInstance and SeededRandom
Tests: 55 new tests for game state models (259 total passing)
Note: GameState imported directly from game_state module to avoid
circular imports with config module.
