Add shared credential envelope infrastructure

alembic/env.py

@@ -12,6 +12,7 @@ except ModuleNotFoundError as exc:
         raise
 from govoplan_core.admin import models as core_admin_models  # noqa: F401 - populate core admin metadata
 from govoplan_core.core import change_sequence as core_change_sequence_models  # noqa: F401 - populate core metadata
+from govoplan_core.security import credential_envelopes as core_credential_models  # noqa: F401 - populate core metadata
 from govoplan_core.core.migrations import migration_metadata_plan
 from govoplan_core.db.base import Base
 from govoplan_core.server.default_config import get_server_config