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/models.py

@@ -46,7 +46,7 @@ class User(AbstractBaseUser, PermissionsMixin):
 
 
 class Family(UUIDModel):
-    name = models.CharField(max_length=255)
+    name = models.CharField(max_length=255, blank=True)
 
     class Meta:
         verbose_name = _("family")
@@ -54,7 +54,12 @@ class Family(UUIDModel):
         ordering = ["name"]
 
     def __str__(self):
-        return self.name
+        if self.name:
+            return self.name
+        surnames = sorted({last_name for last_name in self.memberships.values_list("member__last_name", flat=True) if last_name})
+        if surnames:
+            return _("%(surnames)s family") % {"surnames": " / ".join(surnames)}
+        return _("Family %(id)s") % {"id": str(self.pk)[:8]}
 
     @property
     def guardians(self):
@@ -98,6 +103,11 @@ class Member(UUIDModel):
     def get_short_name(self):
         return self.first_name
 
+    @property
+    def contact_email(self):
+        """Best email to reach this member: own contact email, else login email."""
+        return self.email or (self.user.email if self.user_id else "")
+
     @property
     def guardians(self):
         return Member.objects.filter(