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/scheduler/models.py

@@ -0,0 +1,21 @@
+from django.db import models
+
+
+class JobRun(models.Model):
+    """The record of one run of one job. Owned by `scheduler` (AD-19)."""
+
+    class Status(models.TextChoices):
+        RUNNING = "running"
+        OK = "ok"
+        ERROR = "error"
+
+    job = models.CharField(max_length=60)
+    started_at = models.DateTimeField()
+    finished_at = models.DateTimeField(null=True, blank=True)
+    status = models.CharField(max_length=10, choices=Status.choices, default=Status.RUNNING)
+    # A short summary, or the name of the error. Never personal content.
+    detail = models.CharField(max_length=200, blank=True)
+
+    class Meta:
+        indexes = [models.Index(fields=["job", "-started_at"])]
+        ordering = ["-started_at", "-id"]