Require automatically discovered Hopper launchers to be executable regular
files so POSIX directory search permission cannot hide a later valid
application bundle. Preserve file symlinks, explicit caller configuration,
and the shared candidate ordering.
Cover canonical and renamed user bundles through the production filesystem
predicate; respect existing canonical or renamed system installations in
the isolated fixtures. Clarify launcher eligibility in the installation guide.
Follow-up to #3085 and #3054 after their shared path discovery landed on main.
Co-authored-by: Kaoru0822 <208281322+kaoru0822-kitauji@users.noreply.github.com>
Co-authored-by: gensokyo-dev <342580529+gensokyo-dev@users.noreply.github.com>