Search a live index of ~11.7M developers (GitHub-centric) by role, primary programming language, location, and recent activity — for recruiting, GTM/lead-gen, and developer-audience research. Returns matching GitHub usernames with role, primary language, location, and last-active timestamp. Filters: role (e.g. "backend engineer", "ai/ml engineer"), primary_language (e.g. "Python", "Rust"), location, active_within_days (only devs active in the last N days), sort_by (default last_active). Paginate with limit + offset. Example: revternal_search_developers({ primary_language: "Rust", active_within_days: 30, limit: 20 }).