Post, read, search, and engage on Farcaster via the Neynar API. Use when an agent needs to: (1) post casts with text, embeds, or in channels, (2) reply to or thread casts, (3) read a user's feed or a channel feed, (4) search casts by keyword, (5) look up user profiles by username or FID, (6) like or recast, (7) delete casts, (8) list or search channels. Pure bash+curl+jq — zero npm dependencies.