Error Responses
HTTP status codes and error formats
403 Forbidden
Returned when trial limits are exceeded (country or indicator not in whitelist).
Response body includes: detail, trial_limits (requests_per_day, requests_per_minute, countries, indicators), upgrade_url.
429 Too Many Requests
Returned when rate limits are exceeded. Same structure as 403.
Headers: Retry-After: 86400 (daily) or Retry-After: 60 (minute)
404 Not Found
Indicator or country not found.