feat(domain): add immutable GameState

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/domain/game/game_state.dart

@@ -0,0 +1,68 @@
+import '../../core/config/app_constants.dart';
+import '../entities/pokemon.dart';
+
+/// Phase courante de la partie.
+enum GameStatus { loading, playing, roundWon, gameOver, error }
+
+/// Résultat d'une soumission de réponse.
+enum GuessResult { correct, wrong, gameOver, invalid }
+
+/// État immuable d'une partie.
+class GameState {
+  final Pokemon? currentPokemon;
+  final int lives;
+  final int skips;
+  final int hints;
+  final int sessionCorrectCount;
+  final int currentScore;
+  final int bestScore;
+  final bool isShiny;
+  final bool isHintUsed;
+  final GameStatus status;
+
+  const GameState({
+    this.currentPokemon,
+    this.lives = AppConstants.startingLives,
+    this.skips = AppConstants.startingSkips,
+    this.hints = AppConstants.startingHints,
+    this.sessionCorrectCount = 0,
+    this.currentScore = 0,
+    this.bestScore = 0,
+    this.isShiny = false,
+    this.isHintUsed = false,
+    this.status = GameStatus.loading,
+  });
+
+  GameState copyWith({
+    Pokemon? currentPokemon,
+    int? lives,
+    int? skips,
+    int? hints,
+    int? sessionCorrectCount,
+    int? currentScore,
+    int? bestScore,
+    bool? isShiny,
+    bool? isHintUsed,
+    GameStatus? status,
+  }) {
+    return GameState(
+      currentPokemon: currentPokemon ?? this.currentPokemon,
+      lives: lives ?? this.lives,
+      skips: skips ?? this.skips,
+      hints: hints ?? this.hints,
+      sessionCorrectCount: sessionCorrectCount ?? this.sessionCorrectCount,
+      currentScore: currentScore ?? this.currentScore,
+      bestScore: bestScore ?? this.bestScore,
+      isShiny: isShiny ?? this.isShiny,
+      isHintUsed: isHintUsed ?? this.isHintUsed,
+      status: status ?? this.status,
+    );
+  }
+}
+
+/// Issue d'un appel à GameEngine.submitGuess : nouvel état + nature du résultat.
+class GuessOutcome {
+  final GameState state;
+  final GuessResult result;
+  const GuessOutcome(this.state, this.result);
+}