Add ClubMembership enhancements, CSV import command, and related tests

- Extend the ClubMembership model with `club`, `member`, and optional `license` fields, along with relevant constraints and ordering.
- Implement verbose names for Club and ClubMembership models and update admin configurations for better display and filtering.
- Add a `import_members_csv` management command for batch importing members, clubs, and memberships from a CSV file.
- Include extensive tests for the `import_members_csv` command, ClubMembership model, and Club model.
- Refactor related migrations, services, and test structure.

club/models.py

@@ -2,11 +2,12 @@ from django.contrib.auth.base_user import AbstractBaseUser
 from django.db import models
 from django.utils.translation import gettext_lazy as _
 
+from authentication.models import Member
 from clubmanager.base import ClubScopedModel, UUIDModel
 
 
 class Club(UUIDModel):
-    name = models.CharField(max_length=255)
+    name = models.CharField(_("name"), max_length=255)
 
     class Meta:
         verbose_name = _("club")
@@ -17,4 +18,17 @@ class Club(UUIDModel):
         return self.name
 
 
-class ClubMembership(UUIDModel): ...
+class ClubMembership(UUIDModel):
+    member = models.ForeignKey(Member, on_delete=models.CASCADE, related_name="member_of", verbose_name=_("member"))
+    club = models.ForeignKey(Club, on_delete=models.CASCADE, related_name="members", verbose_name=_("club"))
+
+    license = models.CharField(_("license"), max_length=250, blank=True)
+
+    class Meta:
+        verbose_name = _("club membership")
+        verbose_name_plural = _("club memberships")
+        ordering = ["club", "member__last_name", "member__first_name"]
+        unique_together = ("club", "member")
+
+    def __str__(self):
+        return f"{self.club} - {self.member}"