check-app dies with ENOENT instead of reporting the missing browser when $HOME/browsers is absent #98

When the sandbox setup has not unpacked Chrome's headless shell, $HOME/browsers does not exist at all. The check's glob over that folder then throws ENOENT and check-app dies before it prints a checklist, so the coder sees a crash instead of the finding the check already has words for: "the headless browser is installed ✗ nothing under $HOME/browsers".

Seen on 2026-11-01 on the Compose hub before the arm64 headless shell was available (#29, #81): the design check came back blank with nothing said.

The glob should treat a missing folder as the same finding as an empty one.