libunftp 0.24.0

Changes in this release:

• #583 Document custom SITE commands in the README,
  list unftp-site-hash as an extension, and recommend the unftp-site-* prefix for extension crates.
• #592 Require patched rustls-webpki 0.103.16 or later in
  libunftp to reject compromised eMudhra intermediate CA keys
  (RUSTSEC-2026-0382).
• #582 End a PROXY protocol header read with an
  unexpected EOF error when the peer closes before sending a complete header, avoiding an endless
  read loop.
• BREAKING: #569 Include the FTP working directory in
  DataEvent::Got (RETR) and DataEvent::Put (STOR and APPE) paths. For example, uploading
  photo.jpg in /uploads now reports /uploads/photo.jpg instead of photo.jpg; at the FTP root
  it reports /photo.jpg. Listeners that compare paths or construct storage keys from them must
  handle paths rooted at the user's FTP root rather than raw command arguments. These paths are
  not backend filesystem paths or object URLs, and are not canonicalized. Delete, rename, and
  directory events already use this convention.
• #578 and
  #594 Preserve leading, embedded, and trailing
  whitespace in LIST pathnames, including after options and --.
• #601 Upgrade nix to 0.31.3.