[SizzleUnrlsd]

Closes #219.

GitHub retires its macOS 14 runner images on 2026-11-02 (actions/runner-images#13518). Brownouts already fail macOS 14 jobs: those of #218 failed on 2026-10-31.

Changes

• ci: the build and test matrix runs on macos-15 instead of macos-14.
• ci(release): the macOS disk image is built on macos-15, with a deployment target of 15.0.
  • The image ships Homebrew libraries built for the runner's macOS.
  • package-macos.sh checks those libraries against the target, so a 14.0 target would fail on macos-15.
  • The image therefore needs macOS 15 or newer.
• docs: the README and the reproducibility protocol now say macOS 15, and the README adds that the images up to v0.85.0 also run on macOS 14. The test policy keeps its dated measure on macOS 14.
• docs(changelog): an Unreleased entry says that the disk image needs macOS 15 or newer.

Before merging

The ruleset of main requires Build on macos-14, which this pull request no longer produces. Once the other checks pass, the maintainer replaces that required check with Build on macos-15, then merges.

After that, other open pull requests report the new check only once main is merged into them.

Verification

• Both workflows parse as YAML. Their macOS jobs name macos-15, and the release job sets CMAKE_OSX_DEPLOYMENT_TARGET=15.0.
• scripts/check-license-compliance.sh and scripts/format-check.sh pass.
• The macOS jobs of this pull request test the change. Build on macos-15 builds and runs the tests, and Build macOS binary (arm64) packages the disk image and verifies it.