(bugfix) Preserve scheduled backup warning status

Update the scheduler to reflect the actual scheduled BackupRun status after
a run completes, so prune warnings are shown as schedule warnings instead
of being reported as successful schedule executions.

src/pobsync_backend/management/commands/run_pobsync_scheduler.py

@@ -10,7 +10,7 @@ from django.core.management.base import BaseCommand
 from django.db import transaction
 from django.utils import timezone
 
-from pobsync_backend.models import ScheduleConfig
+from pobsync_backend.models import BackupRun, ScheduleConfig
 from pobsync_backend.scheduler import due_key, is_due
 
 
@@ -52,12 +52,13 @@ class Command(BaseCommand):
             if not is_due(schedule.cron_expr, now):
                 continue
 
+            schedule_started_at = timezone.now()
             with transaction.atomic():
                 locked = ScheduleConfig.objects.select_for_update().get(pk=schedule.pk)
                 if locked.last_due_key == current_due_key:
                     continue
                 locked.last_due_key = current_due_key
-                locked.last_started_at = timezone.now()
+                locked.last_started_at = schedule_started_at
                 locked.last_status = "running"
                 locked.save(update_fields=["last_due_key", "last_started_at", "last_status", "updated_at"])
 
@@ -72,6 +73,7 @@ class Command(BaseCommand):
                     prune_max_delete=schedule.prune_max_delete,
                     prune_protect_bases=schedule.prune_protect_bases,
                 )
+                status = _latest_scheduled_run_status(host_id=schedule.host_id, started_at=schedule_started_at) or status
             except Exception as exc:
                 status = "failed"
                 self.stderr.write(f"{schedule.host.host}: {type(exc).__name__}: {exc}")
@@ -83,3 +85,16 @@ class Command(BaseCommand):
             ran += 1
 
         return ran
+
+
+def _latest_scheduled_run_status(*, host_id: int, started_at) -> str | None:
+    run = (
+        BackupRun.objects.filter(
+            host_id=host_id,
+            run_type=BackupRun.RunType.SCHEDULED,
+            created_at__gte=started_at,
+        )
+        .order_by("-created_at", "-id")
+        .first()
+    )
+    return run.status if run is not None else None