_path_add only ever appended to PATH, which didn't fit profile.d/krew
and profile.d/anyenv (they prepend, to take priority). Rename it to
_path_append for clarity and add _path_prepend alongside it, so both
orderings get the same dedup guard when needed — krew and anyenv
aren't converted yet, kept as plain PATH concatenation until then.
xavier
bbcf389ace