Smoke run 2 (2026-05-11) produced 'UndefinedFunctionError: operator
does not exist: agentrole = role' because postgres had two enums
(role, agentrole) for the same Python class. Information_schema check
confirms no column uses role; migration drops it. Upgrade() raises if
that ever stops being true. Downgrade() recreates the enum with the
foundation's Role values.
Investigation of WHY a second enum got created is tracked in spec E2;
this migration handles the symptom.
Spec ref: docs/superpowers/specs/2026-05-12-post-smoke-3-fixes-design.md
section A5.
