Poll an export job (presigned download URL when completed)

Polls an export job started by POST /business/lists/{listId}/export. While it runs, rowCount and downloadUrl are null. When status is completed, downloadUrl is a short-lived presigned URL for the CSV (poll again for a fresh link once it expires) and rowCount is the number of rows written. When status is failed, error says why: LIST_EMPTY (nothing to export), LIST_NOT_FOUND (the list went away while the job ran) or EXPORT_FAILED (anything else — retry). Unknown or expired jobs answer 404 EXPORT_NOT_FOUND. GET /business/jobs/{jobId} reads the same record and maps error to the same three values.

Errors:

• 404 EXPORT_NOT_FOUND — No export job with that id (it may have expired or belong to another workspace).
• 422 VALIDATION_FAILED — jobId is not a 24-hex id.
• 429 RATE_LIMITED — The lists rate bucket is exhausted.

Requires one of the following token scopes: lists.