bundle: split missing service manager handling

[MikeMcQuaid]

• warn and continue when Linux lacks systemctl, which is common in containers and other non-systemd environments
• keep macOS failing fast because a missing launchctl indicates a broken setup rather than an expected configuration
• cover the shared fallback plus macOS and Linux specific behaviour

Closes #21828 (replaces and implements feedback and fixes merge conflicts)

---

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same change?
• Have you added an explanation of what your changes do and why you'd like us to include them? Performance claims (e.g. "this is faster") must include Hyperfine benchmarks.
• Have you written new tests (excluding integration tests) for your changes? Here's an example.
• Have you successfully run brew lgtm (style, typechecking and tests) with your changes locally?

---

• AI was used to generate or assist with generating this PR. Please specify below how you used AI to help you, and what steps you have taken to manually verify the changes. Non-maintainers may only have one AI-assisted/generated PR open at a time.

Used OpenAI Codex with manual review and tweaks.

---

[Copilot]

Pull request overview

Updates Homebrew::Bundle::Brew::Services.started_services to split the “no service manager available” handling so Linux can warn-and-continue when systemctl is missing (common in containers), while macOS continues to fail fast when launchctl is missing.

Changes:

• Refactor started_services to delegate missing-daemon-manager behavior to started_services_without_daemon_manager.
• Add a Linux-specific override that warns and returns [] when systemctl is missing.
• Expand specs to cover shared fallback behavior plus macOS vs. Linux handling.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
Library/Homebrew/bundle/brew_services.rb	Introduces started_services_without_daemon_manager and routes missing manager behavior through it; loads OS-specific extension.
Library/Homebrew/extend/os/bundle/brew_services.rb	Adds OS dispatch require for the Bundle BrewServices extension.
Library/Homebrew/extend/os/linux/bundle/brew_services.rb	Implements Linux override that warns and returns an empty list when no daemon manager is available.
Library/Homebrew/test/bundle/brew_services_spec.rb	Adds coverage for the fallback method and Linux/macOS-specific behavior.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.