✨(domains) store last check domain results

Store results of last dimail check on a domain.

src/backend/mailbox_manager/migrations/0019_maildomain_last_check_details.py

@@ -0,0 +1,18 @@
+# Generated by Django 5.1.5 on 2025-02-07 20:39
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('mailbox_manager', '0018_maildomain_support_email'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='maildomain',
+            name='last_check_details',
+            field=models.JSONField(blank=True, help_text='A JSON object containing the last health check details', null=True, verbose_name='last check details'),
+        ),
+    ]