Extend admin, migrations, and tests for authentication and club apps

- Implement admin configurations for User, Member, Family, and FamilyMembership, with specialized inlines and filtered displays.
- Introduce `UserCreationForm` and `UserChangeForm` for streamlined user management.
- Enhance Family model with improved string representation and made name optional.
- Add `Member.contact_email` property for prioritized email retrieval.
- Include tests for the updated Family string logic, contact email functionality, and admin integration.
- Add initial migration for club models (Club, ClubMembership) and updated migration for Family in the authentication app.
- Configure IntelliJ IDEA for local SQLite database access.

authentication/forms.py

@@ -0,0 +1,20 @@
+from django.contrib.auth.forms import BaseUserCreationForm
+from django.contrib.auth.forms import UserChangeForm as DjangoUserChangeForm
+
+from .models import User
+
+
+class UserCreationForm(BaseUserCreationForm):
+    """Add-user form for the email-based custom User (no ``username`` field)."""
+
+    class Meta:
+        model = User
+        fields = ("email",)
+
+
+class UserChangeForm(DjangoUserChangeForm):
+    """Change-user form; keeps the read-only password hash widget."""
+
+    class Meta:
+        model = User
+        fields = "__all__"