feat(domain): add pure Pokemon entity and PokemonType enum

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

lib/domain/entities/pokemon.dart

@@ -0,0 +1,71 @@
+/// Entité métier représentant un Pokémon. Pure : aucun import Flutter / DB / API.
+class Pokemon {
+  final String name;
+  final int id;
+  final PokemonType type1;
+  final PokemonType? type2;
+  final int hp;
+  final int atk;
+  final int def;
+  final int spd;
+  final String? description;
+  final bool isCaught;
+  final bool isSeen;
+
+  const Pokemon({
+    required this.name,
+    required this.id,
+    required this.type1,
+    this.type2,
+    required this.hp,
+    required this.atk,
+    required this.def,
+    required this.spd,
+    this.description,
+    this.isCaught = false,
+    this.isSeen = false,
+  });
+
+  String get imageUrl =>
+      'https://raw.githubusercontent.com/Yarkis01/TyraDex/images/sprites/$id/regular.png';
+  String get shinyImageUrl =>
+      'https://raw.githubusercontent.com/Yarkis01/TyraDex/images/sprites/$id/shiny.png';
+  String get cryUrl => 'https://pokemoncries.com/cries/$id.mp3';
+
+  String get formatedName =>
+      name.isEmpty ? name : name[0].toUpperCase() + name.substring(1);
+
+  Pokemon copyWith({
+    String? name,
+    int? id,
+    PokemonType? type1,
+    PokemonType? type2,
+    int? hp,
+    int? atk,
+    int? def,
+    int? spd,
+    String? description,
+    bool? isCaught,
+    bool? isSeen,
+  }) {
+    return Pokemon(
+      name: name ?? this.name,
+      id: id ?? this.id,
+      type1: type1 ?? this.type1,
+      type2: type2 ?? this.type2,
+      hp: hp ?? this.hp,
+      atk: atk ?? this.atk,
+      def: def ?? this.def,
+      spd: spd ?? this.spd,
+      description: description ?? this.description,
+      isCaught: isCaught ?? this.isCaught,
+      isSeen: isSeen ?? this.isSeen,
+    );
+  }
+}
+
+/// Les différents types de Pokémon.
+enum PokemonType {
+  normal, fighting, flying, poison, ground, rock, bug, ghost, steel, fire,
+  water, grass, electric, psychic, ice, dragon, dark, fairy, unknown, shadow
+}