Payment event ledger (PaymentEvent) replicated to the backup server, plus CSV export script on 247

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

payment/migrations/0014_paymentevent.py

@@ -0,0 +1,28 @@
+# Generated by Django 5.2.17 on 2026-10-13 10:47
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('payment', '0013_remove_question_packs'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='PaymentEvent',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('order_id', models.IntegerField(blank=True, db_index=True, null=True)),
+                ('user_id', models.IntegerField(blank=True, db_index=True, null=True)),
+                ('provider', models.CharField(blank=True, max_length=20)),
+                ('event', models.CharField(db_index=True, max_length=40)),
+                ('detail', models.JSONField(blank=True, default=dict)),
+                ('created_at', models.DateTimeField(auto_now_add=True, db_index=True)),
+            ],
+            options={
+                'ordering': ['-created_at'],
+            },
+        ),
+    ]