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/migrations/0002_clubmembership_club_clubmembership_license_and_more.py

@@ -0,0 +1,33 @@
+# Generated by Django 6.0.6 on 2026-07-05 13:50
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('authentication', '0003_alter_family_name_alter_familymembership_family_and_more'),
+        ('club', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='clubmembership',
+            name='club',
+            field=models.ForeignKey(default=1, on_delete=django.db.models.deletion.CASCADE, related_name='members', to='club.club'),
+            preserve_default=False,
+        ),
+        migrations.AddField(
+            model_name='clubmembership',
+            name='license',
+            field=models.CharField(default=1, max_length=250),
+            preserve_default=False,
+        ),
+        migrations.AddField(
+            model_name='clubmembership',
+            name='member',
+            field=models.ForeignKey(default=1, on_delete=django.db.models.deletion.CASCADE, related_name='member_of', to='authentication.member'),
+            preserve_default=False,
+        ),
+    ]

club/migrations/0003_alter_clubmembership_options_alter_club_name_and_more.py

@@ -0,0 +1,43 @@
+# Generated by Django 6.0.6 on 2026-07-05 20:51
+
+import django.db.models.deletion
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('authentication', '0003_alter_family_name_alter_familymembership_family_and_more'),
+        ('club', '0002_clubmembership_club_clubmembership_license_and_more'),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name='clubmembership',
+            options={'ordering': ['club', 'member__last_name', 'member__first_name'], 'verbose_name': 'club membership', 'verbose_name_plural': 'club memberships'},
+        ),
+        migrations.AlterField(
+            model_name='club',
+            name='name',
+            field=models.CharField(max_length=255, verbose_name='name'),
+        ),
+        migrations.AlterField(
+            model_name='clubmembership',
+            name='club',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='members', to='club.club', verbose_name='club'),
+        ),
+        migrations.AlterField(
+            model_name='clubmembership',
+            name='license',
+            field=models.CharField(max_length=250, verbose_name='license'),
+        ),
+        migrations.AlterField(
+            model_name='clubmembership',
+            name='member',
+            field=models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='member_of', to='authentication.member', verbose_name='member'),
+        ),
+        migrations.AlterUniqueTogether(
+            name='clubmembership',
+            unique_together={('club', 'member')},
+        ),
+    ]

club/migrations/0004_alter_clubmembership_license.py

@@ -0,0 +1,18 @@
+# Generated by Django 6.0.6 on 2026-07-05 20:54
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('club', '0003_alter_clubmembership_options_alter_club_name_and_more'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='clubmembership',
+            name='license',
+            field=models.CharField(blank=True, max_length=250, verbose_name='license'),
+        ),
+    ]