docs/ci: refresh README help; add lint; fix ShellCheck; guard /etc/inittab fallback

[VerdantE1]

For commit f3f166a

• Update README minimal help snippet to match current xsos -h output (v0.7.40)
• Document local lint commands in CONTRIB.md
• Add GitHub Actions workflow to run bash -n and shellcheck (errors only)

[VerdantE1]

For commit 2109939:

• Guard the /etc/inittab fallback with a readability check to avoid noisy errors when /etc/inittab is absent.
  Test:bash -n xsos && ./xsos >/dev/null

Why

• On modern Linux distributions (e.g., Ubuntu 22.04+, CentOS 8+, Debian 10+), the /etc/inittab file no longer exists because they use systemd instead of SysV init. This commit adds a simple guard: only read /etc/inittab if it exists and is readable. This eliminates the spurious error while preserving functionality on legacy systems that still have the file.

Changes

• Wrap /etc/inittab access with [ -f /etc/inittab ] && [ -r /etc/inittab ] check
• No change to output logic—just avoids attempting to read a non-existent file

[VerdantE1]

For commit 11cb227:

• Fix ShellCheck error-level findings (SC2068/SC2071) by quoting array expansions / using numeric comparisons, so CI passes.

[superjamie]

Thank you, this looks really good!

I'm currently on holiday. I will review this with intention to merge when I get back in Feb.

[VerdantE1]

Thank you, this looks really good!

I'm currently on holiday. I will review this with intention to merge when I get back in Feb.

Thanks! Enjoy your holiday 😊

[superjamie]

In your docs commit you appear to have removed parsing of the ss and firewall options. Please don't remove those.

As you are fixing up that commit anyway, please also don't add the extra whitespace in the bash-completion file.

I am not sure why the 4th commit is there. It looks to be just a Merge commit adding the same changes again? If so, there is no need for that commit, just the three commits which make the changes.

The other things look okay and ready to merge, good work.

(I am not familiar with Gitub CI but the yaml makes sense)

[VerdantE1]

I've updated the PR as requested:

• Restored the ss and firewall parsing options in the documentation.
• Cleaned up the extra whitespace in the bash-completion file.
• Rebased and squashed the history into 3 clean commits (removed the extra merge commit).
  Thanks for the guidance, please let me know if there's anything else!