Using firecrawl-build-search: Start from queries and write web discovery into product code

`firecrawl-build-search` is an official Agent Skill for Firecrawl, specifically designed to connect the `/search` endpoint to product code: the functionality starts from queries instead of URLs. It first discovers, ranks and selects sources, then decides whether to hydrate the content or hand it over to `/scrape`. This article cross-verifies installation commands, authentication fields, one-step/two-step call differences, and error-prone upgrade paths such as paper indexing and developer indexing based on GitHub's SKILL.md, repository README, officialskills.sh and docs.firecrawl.dev.