Submit an asynchronous bulk export of week-pinned company intent
rows for the requested topics. Streams the result set as JSONL to
cloud storage; returns an export_id to poll via
GET /v1/buyer-intent/exports/{exportId} (cexp_-prefixed).

Credit cost: topic-based, charged at submit time —
base + perTopic × (number of distinct topics), on the same schedule as
the contact export: a 50-credit base plus 5 credits per distinct topic.
Duplicate topic_ids are de-duplicated before the charge. A failed or
timed-out job is refunded.