fclairamb/ftpserverlib — reverse-engineered prompt

Build me a lightweight Go library that lets another developer plug an FTP server into their app without writing the FTP protocol themselves.

I want it to handle normal FTP client behavior like logging in, uploading and downloading files, listing folders, renaming and deleting files, resuming transfers, passive and active connections, IPv6, TLS for control and transfers, and common FTP extras like file size, modified time, hashes, machine readable listings, compression, and combining files. The storage layer should be flexible, so make it work through an afero style filesystem driver, with a simple main driver for settings, welcome messages, authentication, TLS config, and per client file access.

Please keep it small and clean, mostly standard library Go, with structured logging, good connection timeouts, graceful client disconnects, and tests that prove common FTP commands work. Include a clear README with a minimal example showing how someone implements the driver and starts the server.