-- #137. TMDB deletes whole seasons as well as episodes (#122). A season that
-- vanished upstream with a file anywhere under it cannot be deleted — the
-- file row would orphan — so it is flagged instead, the same conflict marker
-- episodes carry. Seasons without any file cascade away outright.
ALTER TABLE seasons ADD COLUMN vanished INTEGER NOT NULL DEFAULT 0
    CHECK (vanished IN (0, 1));