Phase D: location of the user’s optional config file. We use
dirs::config_dir() rather than data_dir() so this lives in the
platform-appropriate “preferences” directory (macOS
~/Library/Application Support, Linux ~/.config, Windows
%APPDATA%). Doesn’t have to exist — load_relays returns an
empty list if absent.
huddle 0.8: optional override for the local Tor SOCKS5 proxy address
used to reach .onion server URLs (default 127.0.0.1:9050). Set in
config.toml as tor_socks = "127.0.0.1:9150" — e.g. to use the Tor
Browser bundle’s port. --tor-socks overrides this. None if absent.