Download an HTTP or HTTPS URL through MoonBit's policy-visible HTTP client.Supports -q/--quiet, -O/--output-document, -o/--output-file, and--idle-timeout SECONDS (default 30, positive fractional values accepted).Downloads show progress on stderr; -q suppresses progress and summaries.Errors remain available in -q mode unless -o FILE routes them to a log.Progress updates are throttled and use a single terminal status line. With-o FILE, all progress and failure diagnostics are written to FILE andstderr remains untouched.HTTP 400 and later responses fail without creating a successful output file.-O - streams the response body to stdout.It does not invoke a host wget executable; recursive downloads, headers,uploads, and certificate bypasses are intentionally unsupported.