Fix the workspace build broken in be65af1

The workspace has not compiled on main since #2 merged. Three breaks,
all from that PR:

- walgit-server calls tempfile::NamedTempFile in lfs.rs, which is
  library code, while tempfile was only a dev-dependency. Move it to
  [dependencies].

- NodelayListener stopped satisfying axum's Connected bound after the
  switch to into_make_service_with_connect_info, which cascaded into
  "WithGracefulShutdown is not a future". axum implements Connected for
  TcpListener and, blanket, for TapIo; a hand-written impl for our own
  listener is refused by the orphan rule (E0117 — the local type is
  covered by the foreign IncomingStream). Drop the nodelay call from
  accept() and disable Nagle through Listener::tap_io instead, so the
  blanket TapIo impl supplies ConnectInfo. Behaviour is unchanged.

- walgit-git's receive test called unwrap_err() on a Result whose Ok
  variant holds a PrefixedReader, which is not Debug. Only
  --all-targets reaches it, so cargo check -p walgit-server misses it.