fix: commit migration role assumption

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a02b22-9638-76d2-bbff-b7ea1770b118

src/sbom_nexus/database.py

@@ -21,7 +21,7 @@ from sqlalchemy import (
     create_engine,
     event,
 )
-from sqlalchemy.engine import Engine
+from sqlalchemy.engine import Connection, Engine
 
 NAMING_CONVENTION = {
     "ix": "ix_%(table_name)s_%(column_0_name)s",
@@ -130,6 +130,15 @@ def database_url(value: str | Path) -> str:
     return text
 
 
+def assume_migration_role(connection: Connection, role: str) -> None:
+    """Assume the durable owner without leaving Alembic inside an outer txn."""
+    connection.exec_driver_sql(f'SET ROLE "{role}"')
+    # SQLAlchemy 2 autobegins on SET ROLE. Commit that transaction before
+    # Alembic opens its own so the migration transaction is not rolled back
+    # when the connection closes. SET ROLE remains active for the session.
+    connection.commit()
+
+
 def _dynamic_connection_factory(url_file: Path):
     def connect():
         try: