What's Changed

Fix: Hang on exit (#41)

Three targeted fixes for the shutdown hang reported in #41:

• Bounded IPv6 echo drain loop — The poll_ipv6_echo_reply drain loop now caps at 256 packets per batch and checks the cancellation token, preventing starvation when the socket is continuously readable
• Ctrl+C force-exit handler — tokio::signal::ctrl_c() handler works outside crossterm raw mode; first press cancels gracefully, second press force-exits with code 130
• Shutdown tracing — Set TTL_SHUTDOWN_TRACE=1 to see timestamped shutdown progress logs on stderr, useful for diagnosing any remaining hang scenarios

Full Changelog: https://github.com/lance0/ttl/compare/v0.16.0...v0.16.1