Remove RefereeLevel.ordering now inherits_from covers the same need

A separate manually-kept number for "which tier is higher" is
redundant now that the inheritance chain already expresses it, and
risked drifting out of sync with it. Levels list/sort by name only.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ECGMEwrc2k4D8VQuwjstj9

teams/migrations/0012_alter_refereelevel_options_and_more.py

@@ -0,0 +1,21 @@
+# Generated by Django 6.0.6 on 2026-08-20 21:02
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('teams', '0011_refereelevel_inherits_from'),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name='refereelevel',
+            options={'ordering': ['name'], 'verbose_name': 'referee level', 'verbose_name_plural': 'referee levels'},
+        ),
+        migrations.RemoveField(
+            model_name='refereelevel',
+            name='ordering',
+        ),
+    ]