e3c5ebb337
Backend: - GET /api/staff/me — returns current staff record (includes isSuperUser) - PATCH /api/staff/:id — accepts optional isSuperUser boolean; only super users can change this field; last-super-user guardrail prevents revoking the only active super user - PATCH /api/staff/:id (active=false) — guardrail prevents deactivating the last active super user - DELETE /api/staff/:id — guardrail prevents deleting the last active super user Frontend (Staff.tsx): - Fetches current user via GET /api/staff/me to determine isSuperUser - Shows ★ Super User badge for super user staff rows - Super user sees "+ Grant" button on non-super-user rows - Super user sees "Revoke" toggle on super-user rows (disabled if last one) - Deactivate button disabled for the last active super user - Error message displayed when backend guardrail triggers GRO-206 Co-Authored-By: Paperclip <noreply@paperclip.ing>