-- Claimed-by can now optionally link to a real Creator Group (picked from
-- a dropdown of existing ones) instead of only ever being free text --
-- rendered as a real link, same as a key claimed through the actual
-- system already is via its redemption's claim link. Free text still
-- works for a claimant that genuinely isn't a known creator group; the two
-- are mutually exclusive per key (see keys_pool.php's set_claimed_by
-- handler), so only one of claimed_by_note/claimed_by_creator_group_id is
-- ever set at a time.

ALTER TABLE `keys` ADD COLUMN claimed_by_creator_group_id INT UNSIGNED NULL AFTER claimed_by_note;
ALTER TABLE `keys` ADD CONSTRAINT fk_key_claimed_by_creator_group FOREIGN KEY (claimed_by_creator_group_id) REFERENCES creator_groups(id) ON DELETE SET NULL;
