Free, capped preview of the account-discovery direction: given a
topic_id, return a small sample (up to 25) of the top companies, ranked by
people_count, plus the topic's total count. Use it to show a teaser while
configuring a source, then call the paid /api/v1/intent/companies to pull
and pay for the full list.

Nothing is billed. Distinct from dry_run (which returns a cost count and no
records): this returns actual sample records. It does not paginate (no
cursor, no next_cursor); you always get the strongest-intent top of the
list. count is the topic's full company total, so the sample is only a
window onto it.