Don't panic on broken pipe (e.g. npmctl list-hosts | head)

Reset SIGPIPE to SIG_DFL at startup so writing to a closed stdout
terminates the process quietly like normal Unix tools, instead of
panicking with "failed printing to stdout: Broken pipe".

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011YPrEZVBpPVoCRyJz2exkZ

Cargo.lock

@@ -629,6 +629,7 @@ dependencies = [
  "chrono",
  "clap",
  "dirs",
+ "libc",
  "reqwest",
  "rpassword",
  "serde",