Add Teams endpoint and endpoints with service

frontend_splatournament_manager/lib/models/team.dart

@@ -0,0 +1,36 @@
+class Team {
+  final int id;
+  final String name;
+  final String tag;
+  final String description;
+  final String createdAt;
+
+  Team({
+    required this.id,
+    required this.name,
+    required this.tag,
+    required this.description,
+    required this.createdAt,
+  });
+
+  factory Team.fromJson(Map<String, dynamic> json) {
+    return Team(
+      id: json['id'] as int,
+      name: json['name'] as String,
+      tag: json['tag'] as String,
+      description: (json['description'] as String?) ?? '',
+      createdAt: (json['createdAt'] as String?) ?? '',
+    );
+  }
+
+  Map<String, dynamic> toJson() {
+    return {
+      'id': id,
+      'name': name,
+      'tag': tag,
+      'description': description,
+      'createdAt': createdAt,
+    };
+  }
+}
+