fix(marmot-interop): clean up daemons on Ctrl+C / SIGTERM / SIGHUP

The previous trap only fired on the EXIT pseudo-signal, which doesn't
always run cleanly when the script is killed mid-flight — leaving the
nohup'd wnd daemons (and the local relay) alive and still holding the
port. Route SIGINT/SIGTERM/SIGHUP through an explicit `exit`, use a
single idempotent cleanup handler, and preserve the exit code so the
harness still reports failure when killed.

tools/marmot-interop/marmot-interop-headless.sh

@@ -80,7 +80,22 @@ source "$SCRIPT_DIR/headless/tests-manage.sh"
 # shellcheck source=headless/tests-extras.sh
 source "$SCRIPT_DIR/headless/tests-extras.sh"
 
-trap 'stop_daemons; stop_local_relay; print_summary' EXIT
+# Make sure Ctrl+C / SIGTERM / SIGHUP all run the full cleanup path —
+# otherwise wnd is nohup'd and keeps running after the script dies,
+# and the next run's `ss` check then complains the port is in use.
+# Trap INT/TERM/HUP forces `exit`, which triggers the EXIT handler once.
+cleanup() {
+  local rc=$?
+  trap - EXIT INT TERM HUP
+  stop_daemons
+  stop_local_relay
+  print_summary
+  exit "$rc"
+}
+trap cleanup EXIT
+trap 'exit 130' INT
+trap 'exit 143' TERM
+trap 'exit 129' HUP
 
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