Add latest option to mirror update task

[alloutflo]

Summary

• expose an optional latest Boolean on the mirror_update task
• pass -latest to aptly only when the option is enabled
• cover both enabled and omitted behavior, including task pass-through
• regenerate REFERENCE.md with Puppet Strings

Fixes #91

Verification

• bundle exec rspec spec/unit/cli_helper_spec.rb spec/tasks/mirror_spec.rb — 34 examples, 0 failures
• bundle exec rspec spec/tasks spec/unit/cli_helper_spec.rb — 59 examples, 0 failures
• bundle exec rake validate lint check rubocop
• git diff --check
• Upstream CI — 10/10 checks passed, including static validation, the test suite, and all supported OpenVox platform jobs

AI assistance

OpenAI Codex assisted with repository analysis, implementation, regression coverage, and PR preparation. The resulting diff was inspected and the checks listed above were executed before submission.

[jay7x]

@alloutflo Hello! Thank you for the contribution!
While technically the PR is good (it follows the original style well), I didn't get the part about "Ruby 4.0 baseline" in the description.. 🤔

[alloutflo]

Thanks — you're right, “Ruby 4.0 baseline” was confusing. It referred only to my local Ruby 4.0.6 environment, where the full task encountered unrelated compatibility failures; it was not a project baseline or a concern with this change. Since the supported upstream CI has now completed with 10/10 checks green, I've removed that section and updated the description to show the actual CI result.