Function sync_hosts_file 

pub fn sync_hosts_file(bind_ip: &str, tld: &str)

Sync all registered slug hostnames into /etc/hosts.

Reads the current slug table from global config, builds the expected hosts block, and replaces (or appends) the pitchfork-managed block.

Best-effort: logs a warning on failure (e.g. permission denied) and does not prevent proxy startup.