Add defense-in-depth sanitization for OpenResty include files to prevent
OS command injection via malicious filenames that break shell quoting in eval.
- Add filename validation in core-post-extract using regex [^a-zA-Z0-9_.-]
- Validate both http-includes and location-includes paths
- Abort deploy via dokku_log_fail on unsafe filenames
- Skip non-regular files (symlinks, directories) during extraction
- Add security regression test with unsafe filename containing space
- Keep existing guards in docker-args-process-deploy as belt-and-suspenders
- Update documentation to clarify allowed filename characters
Addresses CVSS 9.9 vulnerability where filenames like poc'$(cmd)'x.conf
could escape shell quoting and execute arbitrary commands during deploy.