Allow oversight_admin users to view the User Management screen with
read-only access. They can see users, roles, agencies, and change
history but cannot edit roles, assign agencies, or create agencies.
Backend: open GET /users and GET /users/{id}/change-history to
oversight_admin (PUT /users stays super_admin only).
Frontend: add oversight_admin to sidebar nav and context permission,
render static text instead of dropdowns and hide the add-agency form
for non-super-admin users.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
a25c7a9d31