Fix copilot-setup-steps.yml to properly install Dist::Zilla and its plugins

[Copilot]

cpanm --installdeps --with-develop --notest . silently fails for Dist::Zilla projects — there is no META.json or Makefile.PL in the repo root (both are generated by dzil build), so cpanm has nothing to read.

Changes

• Replace the single broken install step with the standard three-step Dzil bootstrap:

- name: Install Dist::Zilla
  run: cpanm --notest Dist::Zilla

- name: Install Dist::Zilla author dependencies
  run: dzil authordeps --missing | cpanm --notest

- name: Install application dependencies
  run: dzil listdeps --missing | cpanm --notest

• authordeps installs all Dzil plugins declared in dist.ini ([@Classic], [PodWeaver], [@Git], [Test::Compile], etc.)
• listdeps installs runtime/test prereqs (Plack::Runner, Config::Tiny, etc.) declared under [Prereqs]

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Ensure .github/workflows/copilot-setup-steps.yml handles Dzil requirements</issue_title>
<issue_description>I know little about Dzil and I'm worried that the steps in .github/workflows/copilot-setup-steps.yml won't ensure we have all the correct Dzil plugins pre-installed. Please check and make the appropriate comments.</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Ensure .github/workflows/copilot-setup-steps.yml handles Dzil requirements #8

---

🔒 GitHub Advanced Security automatically protects Copilot coding agent pull requests. You can protect all pull requests by enabling Advanced Security for your repositories. Learn more about Advanced Security.