Add the management app: club-facing UI + real fee-payment tracking

Gives clubs a self-service /manage/ area for members, families, teams,
roles, and season memberships, alongside real fee-payment tracking
(FeePayment, record_payment/mark_as_paid/remaining_balance) so a
membership's paid status reflects actual money received instead of a
single manually-set flag.

club/migrations/0016_clubmembership_amount_paid_clubmembership_fee_amount_and_more.py

@@ -0,0 +1,50 @@
+# Generated by Django 6.0.6 on 2026-08-03 11:22
+
+import django.core.validators
+import django.db.models.deletion
+import django.utils.timezone
+import uuid
+from decimal import Decimal
+from django.conf import settings
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('club', '0015_alter_club_logo'),
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='clubmembership',
+            name='amount_paid',
+            field=models.DecimalField(blank=True, decimal_places=2, default=Decimal('0.00'), help_text='Kept in step with payments by the fee service; not hand-edited.', max_digits=10, verbose_name='amount paid'),
+        ),
+        migrations.AddField(
+            model_name='clubmembership',
+            name='fee_amount',
+            field=models.DecimalField(blank=True, decimal_places=2, default=Decimal('0.00'), max_digits=10, verbose_name='fee amount'),
+        ),
+        migrations.CreateModel(
+            name='FeePayment',
+            fields=[
+                ('created', models.DateTimeField(auto_now_add=True, verbose_name='created')),
+                ('modified', models.DateTimeField(auto_now=True, verbose_name='modified')),
+                ('id', models.UUIDField(default=uuid.uuid4, editable=False, primary_key=True, serialize=False)),
+                ('amount', models.DecimalField(decimal_places=2, max_digits=10, validators=[django.core.validators.MinValueValidator(Decimal('0.01'))], verbose_name='amount')),
+                ('method', models.CharField(choices=[('bank_transfer', 'bank transfer'), ('cash', 'cash'), ('card', 'card'), ('other', 'other')], default='bank_transfer', max_length=20, verbose_name='method')),
+                ('reference', models.CharField(blank=True, help_text='Bank reference, transaction id — whatever lets you find this again.', max_length=255, verbose_name='reference')),
+                ('paid_at', models.DateTimeField(default=django.utils.timezone.now, verbose_name='paid at')),
+                ('note', models.TextField(blank=True, verbose_name='note')),
+                ('membership', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='payments', to='club.clubmembership', verbose_name='membership')),
+                ('recorded_by', models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='recorded_fee_payments', to=settings.AUTH_USER_MODEL, verbose_name='recorded by')),
+            ],
+            options={
+                'verbose_name': 'fee payment',
+                'verbose_name_plural': 'fee payments',
+                'ordering': ['-paid_at'],
+            },
+        ),
+    ]