fix(installer): enlist table retirement transaction

src/govoplan_core/core/module_guards.py

@@ -79,15 +79,19 @@ def drop_table_retirement_provider(
             warnings.append("Tables not present and therefore skipped: " + ", ".join(missing_names))
 
         def executor(execute_session: object, _module_id: str) -> None:
-            if not hasattr(execute_session, "get_bind"):
+            if not hasattr(execute_session, "connection"):
                 raise RuntimeError("No database session is available for destructive table retirement.")
-            execute_bind = execute_session.get_bind()  # type: ignore[attr-defined]
-            live_inspector = inspect(execute_bind)
+            # Enlist schema retirement in the caller's active transaction.  An
+            # Engine returned by Session.get_bind() may acquire a second
+            # connection, separating the DROP from module-specific secret
+            # scrubbing/audit writes and deadlocking on their uncommitted locks.
+            execute_connection = execute_session.connection()  # type: ignore[attr-defined]
+            live_inspector = inspect(execute_connection)
             live_tables = [table for table in tables if live_inspector.has_table(table.name)]
             if not live_tables:
                 return
             metadata = live_tables[0].metadata
-            metadata.drop_all(bind=execute_bind, tables=live_tables, checkfirst=True)
+            metadata.drop_all(bind=execute_connection, tables=live_tables, checkfirst=True)
 
         return MigrationRetirementPlan(
             supported=True,