Fix macOS x86_64 packaging: add Homebrew paths for Intel runners

[Copilot]

The macOS x86_64 CI packaging was failing because the compiler couldn't find Homebrew-installed FFTW and other system libraries. The workflow only set CPATH and LIBRARY_PATH for ARM runners (macos-14), not Intel runners (macos-13).

Changes:

• Extended Homebrew path setup from ARM-only (matrix.os == 'macos-14') to all macOS runners (runner.os == 'macOS')
• brew --prefix automatically resolves to /opt/homebrew on ARM and /usr/local on x86_64

# Before: only ARM macOS
- name: Set up Homebrew paths on ARM macOS
  if: ${{ matrix.os == 'macos-14' }}

# After: all macOS
- name: Set up Homebrew paths on macOS
  if: ${{ runner.os == 'macOS' }}

Original prompt

---

This section details on the original issue you should resolve

<issue_title>CI: macOS x86_64 packaging is broken</issue_title>
<issue_description>https://github.com/light-curve/light-curve-python/actions/runs/19038835966/job/54370213018</issue_description>

<agent_instructions>For some reason macOS x86_64 packaging CI in github actions stopped working, complaining about FFTW linking. Can you debug it on macos x86_64?</agent_instructions>

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

• Fixes CI: macOS x86_64 packaging is broken #573

---

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[codspeed-hq]

CodSpeed Performance Report

Merging #578 will not alter performance

_{Comparing copilot/debug-macos-x86-64-packaging (b700dc7) with master (d178dbe)}

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

Summary

✅ 106 untouched
⏩ 106 skipped¹

Footnotes

1. 106 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[hombit]

Nice work

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 82.60%. Comparing base (d178dbe) to head (b700dc7).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #578   +/-   ##
=======================================
  Coverage   82.60%   82.60%           
=======================================
  Files           9        9           
  Lines        2604     2604           
=======================================
  Hits         2151     2151           
  Misses        453      453           

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