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>

club/migrations/0021_club_legal_name.py

@@ -0,0 +1,18 @@
+# Generated by Django 6.0.6 on 2026-08-09 18:19
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('club', '0020_sponsor_logo_height_sponsor_logo_width'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='club',
+            name='legal_name',
+            field=models.CharField(blank=True, help_text='Full registered name (e.g. including a legal form like VZW/ASBL), used on official documents. Falls back to the name above when left blank.', max_length=255, verbose_name='legal name'),
+        ),
+    ]