fix(playable): close release validation lifecycle gaps

script/forest_map_render_test.sh

@@ -26,6 +26,7 @@ timeout_seconds=900
 required_arch="${MT_PLAYABLE_REQUIRED_ARCH:-arm64}"
 kill_grace_seconds=10
 suite="forest_render"
+source script/playable_process_cleanup.sh
 
 usage() {
   cat <<'EOF'
@@ -181,6 +182,7 @@ while kill -0 "$child_pid" 2>/dev/null; do
 done
 wait "$child_pid"
 process_code=$?
+child_pid=""
 
 node script/validate_playable_report.mjs --report "$client_report" --output "$final_report" \
   --log "$log" --process-code "$process_code" --timed-out "$timed_out" --run-id "$run_id" \