The flag overrides the kill refusal (#81): the session ends, the guarded
worktree is retained, and the CLI prints where the work went — path,
branch, force-killed — instead of leaving the operator to wonder.
WORKTREES.md: write down that a forced kill of a tree whose guard is
clear removes it as usual — force changes what happens to blocked work,
not ordinary cleanup.
Miguel Palhas
0c135aa065