✨(backend) add a flexible JSON field to store recording options

Using a JSON field allows iterating on recording data without running a new
migration each time additional options or metadata need to be tracked.

This comes with trade-offs, notably weaker data validation and less clarity on
which data can be stored alongside a recording.

In the long run, this JSON field can be refactored into dedicated columns once
the feature and data model have stabilized.

src/backend/core/migrations/0016_recording_options.py

@@ -0,0 +1,18 @@
+# Generated by Django 5.2.9 on 2025-12-29 15:30
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0015_application_and_more'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='recording',
+            name='options',
+            field=models.JSONField(blank=True, default=dict, help_text='Recording options', verbose_name='Recording options'),
+        ),
+    ]