-- migrate:up
--
-- Data hygiene: 1 vehicle had `assigned_city = 'Nairobi'` while the other
-- 54 had `'nairobi'`. Collapse to lower-case so the filter dropdown shows
-- a single canonical option. The projector doesn't set assigned_city (it
-- comes from manual edits / roster imports) so no other code change is
-- needed to prevent recurrence.

UPDATE domain.vehicles
   SET assigned_city = trim(lower(assigned_city)),
       updated_at = now()
 WHERE assigned_city IS NOT NULL
   AND assigned_city != trim(lower(assigned_city));

-- migrate:down
-- No-op: re-introducing inconsistent casing would be a regression.