Reject case variants of shipped profile names, detect a concurrent winner by
the target's state instead of errno, warn instead of failing when staging
cleanup fails after a successful replacement, and cover the restore paths with
deterministic tests. Update the profile Agent Note, reference recovery path,
and upgrade-guide migration steps.
Repeated rescue runs such as `dsh rescue --from-default-profile web` failed
because the target profile already existed. The option now assembles a fresh
template copy in a staging directory, moves it over the target, and deletes the
previous profile; a failed move restores it.
Turtle