A bank's external slug. Historically a literal union of the seeded set;
now a plain string so admin operators can mint new bank rows from the
dashboard. The slugs in BANK_IDS retain their special-case
behavior across services; any other string is a regular partner bank.
A bank's external slug. Historically a literal union of the seeded set; now a plain string so admin operators can mint new bank rows from the dashboard. The slugs in BANK_IDS retain their special-case behavior across services; any other string is a regular partner bank.