fix(campaign): honor acceptance temp selection

tests/test_celery_redelivery_acceptance.py

@@ -172,6 +172,19 @@ def test_worker_bootstrap_uses_real_late_ack_solo_celery_worker() -> None:
     assert "send_email.run" not in source
 
 
+def test_runtime_root_uses_platform_temp_selection() -> None:
+    with mock.patch(
+        "govoplan_campaign_celery_redelivery_acceptance.tempfile.mkdtemp",
+        return_value="/selected-temp/govoplan-campaign-celery-redelivery-test",
+    ) as mkdtemp:
+        runtime_root = runner._create_runtime_root()
+
+    assert runtime_root == Path(
+        "/selected-temp/govoplan-campaign-celery-redelivery-test"
+    )
+    mkdtemp.assert_called_once_with(prefix="govoplan-campaign-celery-redelivery-")
+
+
 def test_worker_log_projection_matches_redelivered_task_without_retaining_id() -> None:
     with tempfile.TemporaryDirectory() as temporary_directory:
         log_path = Path(temporary_directory) / "worker.log"