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/management/commands/send_test_mail.py

@@ -0,0 +1,28 @@
+from django.core.management.base import BaseCommand, CommandError
+
+from portal.mailer import services
+from portal.mailer.models import OutboxMail
+
+
+class Command(BaseCommand):
+    help = "Queue a test e-mail and send it now, to check the SMTP settings."
+
+    def add_arguments(self, parser):
+        parser.add_argument("recipient", help="E-mail address that should receive the test mail")
+
+    def handle(self, *args, recipient, **options):
+        try:
+            mail = services.enqueue("test", recipient)
+        except ValueError as exc:
+            raise CommandError(str(exc)) from exc
+        result = services.flush()
+        mail.refresh_from_db()
+        self.stdout.write(f"Outbox entry {mail.pk}: {mail.status} ({result})")
+        if mail.status == OutboxMail.Status.SENT:
+            self.stdout.write("The mail server accepted the message.")
+        elif mail.status == OutboxMail.Status.QUEUED:
+            self.stdout.write(f"Not sent yet, will be retried: {mail.last_error}")
+            raise SystemExit(1)
+        else:
+            self.stdout.write(f"Failed: {mail.last_error}")
+            raise SystemExit(1)