Add referee assignment/eligibility system, team bulk-add, member Groups, and referee management dashboard with PDF export

Builds the referee workflow end to end: club-defined RefereeLevel/RefereeProfile
eligibility tied to teams, EventReferee assignment (member or external, with
fee/km payment tracking), an admin dashboard with KPI tiles, date-grouped game
tiles and range filters, and a downloadable payment form PDF modeled on the
club's existing paper document (using Club.legal_name when set). Also lands
team roster bulk-add, member mass-upload with family linking, and the
members.Group model, developed alongside this work.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

events/migrations/0020_event_max_referees_eventreferee.py

@@ -0,0 +1,38 @@
+# Generated by Django 6.0.6 on 2026-08-08 21:55
+
+import django.db.models.deletion
+import uuid
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('events', '0019_competition_sport_type'),
+        ('members', '0004_group_groupmembership_and_more'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='event',
+            name='max_referees',
+            field=models.PositiveSmallIntegerField(default=2, help_text='How many referees can be assigned to this game. Only meaningful for home games -- ignored otherwise.', verbose_name='max referees'),
+        ),
+        migrations.CreateModel(
+            name='EventReferee',
+            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)),
+                ('assigned_by', models.ForeignKey(null=True, on_delete=django.db.models.deletion.SET_NULL, related_name='+', to='members.member', verbose_name='assigned by')),
+                ('event', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='referees', to='events.event', verbose_name='event')),
+                ('member', models.ForeignKey(on_delete=django.db.models.deletion.CASCADE, related_name='referee_assignments', to='members.member', verbose_name='member')),
+            ],
+            options={
+                'verbose_name': 'event referee',
+                'verbose_name_plural': 'event referees',
+                'ordering': ['event', 'member__last_name', 'member__first_name'],
+                'constraints': [models.UniqueConstraint(fields=('event', 'member'), name='unique_referee_per_event')],
+            },
+        ),
+    ]