The hygiene pass (e960eda) dropped path=(~/.cache/lk-tools/fzf/bin $path) as
stale. On Linux boxes set up by lk-installers/install-apps it is the only thing
that puts fzf on PATH (install-apps vendors fzf there and relies on .zshrc to
add it), so fzf, fzf-tab and fzf-git broke in new shells. Restored behind an
existence guard, matching that commit's only-if-installed style, so boxes
without the vendored copy are unaffected.