0c1fd7f5d8
clap consumes the -- marker before execute for the default-signal and -s/-n forms, so kill -- -10 and kill -s TERM -- -10 previously misread the negative PID as a signal. Captured post-marker operands via a dedicated last=true field and treated a preselected -s/-n signal as closing the option position. Added a regression covering both marker-consumed forms. Fixes #6779