feat: add scheduler and mail outbox

SMTP adapter with TLS and a fake, outbox with retries, backoff, rate limit and restart safety, scheduler tick with job-run records started by gunicorn, and a send_test_mail command.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01N3t4WL7bd9bdHHNjEsxzqC

portal/mailer/migrations/0001_initial.py

@@ -0,0 +1,35 @@
+# Generated by Django 5.2.18 on 2026-10-18 07:16
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='OutboxMail',
+            fields=[
+                ('id', models.BigAutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('template', models.CharField(max_length=100)),
+                ('recipient', models.CharField(max_length=254)),
+                ('subject', models.CharField(max_length=300)),
+                ('body_text', models.TextField(blank=True)),
+                ('status', models.CharField(choices=[('queued', 'Queued'), ('sending', 'Sending'), ('sent', 'Sent'), ('failed', 'Failed')], default='queued', max_length=10)),
+                ('attempts', models.PositiveSmallIntegerField(default=0)),
+                ('created_at', models.DateTimeField()),
+                ('next_attempt_at', models.DateTimeField()),
+                ('claimed_at', models.DateTimeField(blank=True, null=True)),
+                ('sent_at', models.DateTimeField(blank=True, null=True)),
+                ('last_error', models.CharField(blank=True, max_length=200)),
+            ],
+            options={
+                'ordering': ['id'],
+                'indexes': [models.Index(fields=['status', 'next_attempt_at'], name='mailer_outb_status_d5af6e_idx')],
+            },
+        ),
+    ]