taskkill compat shim: a11y-first kill routing

v1.6 STRICT POLICY: --force <pid1,pid2,...> is the ONLY way to kill anything via taskkill -- listed PIDs are killed exactly, others survive. All other invocations (/IM, /PID, bare *.exe) are CLASSIFY-ONLY: enumerate matches, print PROTECTED/ZOMBIE/UNKNOWN report, exit 1, kill nothing. v1.6: --force now also prints a PRESERVED block listing every matching PID in scope (from /IM filter, or the wkappbot family if no /IM was given) that was NOT in the --force list, with classification tag. Output ends with 'Killed: N / Preserved: M' summary plus a copy-paste hint when surviving zombies remain. The --force-all flag has been REMOVED. Implementation: TaskkillCompatCommand.cs (TaskkillForcePids) + TaskkillCompatCommand.Classify.cs (TaskkillPrintForceReport). Help text: CommandHelp.cs taskkill entry.

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