Refactor accounts app into authentication and club apps

- Split the accounts app into new authentication and club apps for better separation of concerns.
- Migrate the custom User, Member, and Family models to the authentication app.
- Introduce Club and ClubMembership models in the club app.
- Refactor Family model to use UUID as the primary key and consolidate family-role relationships into a new FamilyMembership model.
- Update tests, managers, and migrations to align with the new structure.

clubmanager/settings.py

@@ -44,11 +44,10 @@ INSTALLED_APPS = [
     "django.contrib.messages",
     "django.contrib.staticfiles",
     "phonenumber_field",
-    "accounts",
+    "club.apps.ClubConfig",
+    "authentication.apps.AuthenticationConfig",
 ]
 
-AUTH_USER_MODEL = "accounts.User"
-
 MIDDLEWARE = [
     "django.middleware.security.SecurityMiddleware",
     "django.contrib.sessions.middleware.SessionMiddleware",
@@ -61,6 +60,8 @@ MIDDLEWARE = [
 
 ROOT_URLCONF = "clubmanager.urls"
 
+AUTH_USER_MODEL = "authentication.User"
+
 TEMPLATES = [
     {
         "BACKEND": "django.template.backends.django.DjangoTemplates",