fix: use local calendar dates in demo seed

tests/integration/test_auth_login.py

@@ -145,15 +145,22 @@ def test_demo_login_logs_in_and_seeds_environment(client):
     assert "minstens één import actief" in sources.content.decode("utf-8")
 
 
-def test_demo_login_is_idempotent(client):
-    from datetime import timedelta
+def test_demo_login_is_idempotent(client, monkeypatch):
+    from datetime import UTC, datetime, timedelta
 
     from django.utils import timezone
 
     from apps.jobs.models import Application, JobPosting
+    from apps.jobs.services import demo_seed
     from apps.profiles.models import SearchProfile
     from apps.sources.models import MailboxConnection, Source
 
+    # 22:30 UTC is already the following calendar day in Europe/Brussels.
+    # Freezing this boundary prevents UTC `.date()` calls from creeping back in.
+    near_local_midnight = datetime(2026, 9, 2, 22, 30, tzinfo=UTC)
+    monkeypatch.setattr(demo_seed.timezone, "now", lambda: near_local_midnight)
+    expected_local_day = timezone.localdate(near_local_midnight)
+
     client.post(reverse("demo-login"))
     first = JobPosting.objects.count()
     demo_user = get_user_model().objects.get(username=settings.DEMO_USERNAME)
@@ -172,8 +179,8 @@ def test_demo_login_is_idempotent(client):
     job.refresh_from_db()
     application.refresh_from_db()
     assert job.status == JobPosting.Status.ACTIVE
-    assert job.last_seen.date() == timezone.localdate()
-    assert application.follow_up_date > timezone.localdate()
+    assert timezone.localdate(job.last_seen) == expected_local_day
+    assert application.follow_up_date > expected_local_day
     assert profile.scores.count() == 6
     assert MailboxConnection.objects.filter(user=demo_user, enabled=True).count() == 9
     assert Source.objects.filter(source_type=Source.Type.EMAIL, failure_count=0).count() >= 9