feat: govern shared campaign artifact storage

tests/test_operational_checks.py

@@ -2,17 +2,17 @@ from __future__ import annotations
 
 from unittest.mock import patch
 
+from govoplan_core.core.object_storage import LocalFilesystemStorageBackend
 from govoplan_campaign.backend.operational_checks import generated_eml_storage_check
 
 
 def test_generated_eml_probe_reports_node_local_boundary(tmp_path) -> None:
     with patch(
-        "govoplan_campaign.backend.operational_checks.BUILD_OUTPUT_DIR",
-        tmp_path,
+        "govoplan_campaign.backend.operational_checks.configured_storage_backend",
+        return_value=LocalFilesystemStorageBackend(tmp_path),
     ):
         result = generated_eml_storage_check()
 
     assert result.state == "warning"
     assert "node-local" in result.detail
     assert list(tmp_path.rglob("*.probe")) == []
-