Cross-compilation and macOS compatibility fixes (#1)

- Ethernet ioctl: cfg-gate the ioctl request parameter type — c_int on
  musl, c_ulong on gnu — so the same code compiles on both
  x86_64-unknown-linux-gnu and x86_64-unknown-linux-musl targets

- Chaos harness macOS support: replace direct host 'ip link' invocations
  with a privileged Docker container helper (--net=host --pid=host) that
  shares the Docker VM's namespaces, making veth pair setup work on both
  Linux and macOS (where host 'ip' is unavailable and container PIDs
  live inside the Docker Desktop VM)

- Python 3.9 compat: add 'from __future__ import annotations' to
  docker_exec.py for X|Y union syntax support

- Add deploy/ to .gitignore

Co-authored-by: origami74 <origami74@gmail.com>

.gitignore

@@ -13,3 +13,5 @@
 
 # Claude Code
 .claude/
+
+deploy/