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/services.py

@@ -0,0 +1,48 @@
+"""Jobs and one tick that runs them (AD-12).
+
+Every job reads the database for what is due and is safe to repeat, so a missed or doubled
+tick does no harm. Each run is recorded for the Admin status page.
+"""
+
+from __future__ import annotations
+
+import logging
+from collections.abc import Callable
+from dataclasses import dataclass
+from datetime import datetime, timedelta
+
+from django.utils import timezone
+
+from portal.mailer import services as mailer
+
+from .models import JobRun
+
+logger = logging.getLogger(__name__)
+
+KEEP_RUNS_DAYS = 7
+
+
+@dataclass(frozen=True)
+class Job:
+    name: str
+    run: Callable[[datetime], object]  # returns something printable as the run's summary
+
+
+# The order is the order they run in. Later entries add jobs here.
+JOBS: tuple[Job, ...] = (Job("mail.flush", lambda now: mailer.flush(now)),)
+
+
+def tick(now: datetime | None = None, jobs: tuple[Job, ...] | None = None) -> None:
+    """Run every job once. A failing job is recorded and does not stop the others."""
+    now = now or timezone.now()
+    for job in JOBS if jobs is None else jobs:
+        run = JobRun.objects.create(job=job.name, started_at=now)
+        try:
+            detail = str(job.run(now))
+            status = JobRun.Status.OK
+        except Exception as exc:
+            logger.exception("Job %s failed", job.name)
+            detail, status = type(exc).__name__, JobRun.Status.ERROR
+        run.status, run.detail, run.finished_at = status, detail[:200], timezone.now()
+        run.save(update_fields=["status", "detail", "finished_at"])
+    JobRun.objects.filter(started_at__lt=now - timedelta(days=KEEP_RUNS_DAYS)).delete()