Get the states or regions in a country. Use this after the user picks a country. Returns states with their codes, sorted by name. Use a state's value as state_code in List cities.

Prerequisites: a country_code, from List countries.

Authentication: Public (no token). Anyone gets the same global list; a Partner or Account token may be sent, but none is needed.

Rate limit: 100 requests per minute, counted per client IP address.