Firecrawl v2 search as a Perplexed.Search provider.
Never sends scrapeOptions, so a search costs two credits per ten results
and returns snippets only; scrape pages with Perplexed.Scrape instead.
Priced at two credits of Perplexed.Scraper.Firecrawl.credit_usd/0 (the
firecrawl_credit_usd setting).
:country defaults to "US".
Needs config :perplexed, firecrawl_api_key:.